Analysis of Cancer Proteins: Pattern Identification on Escherichia coli Species

Similar documents
CS612 - Algorithms in Bioinformatics

Lecture 3: 8/24. CHAPTER 3 Amino Acids

Amino acids. (Foundation Block) Dr. Essa Sabi

Proteins consist in whole or large part of amino acids. Simple proteins consist only of amino acids.

LAB#23: Biochemical Evidence of Evolution Name: Period Date :

Activities for the α-helix / β-sheet Construction Kit

Midterm 1 Last, First

Section 1 Proteins and Proteomics

Protein Folding LARP

Amino Acids. Amino Acids. Fundamentals. While their name implies that amino acids are compounds that contain an NH. 3 and CO NH 3

Gentilucci, Amino Acids, Peptides, and Proteins. Peptides and proteins are polymers of amino acids linked together by amide bonds CH 3

Page 8/6: The cell. Where to start: Proteins (control a cell) (start/end products)

So where were we? But what does the order mean? OK, so what's a protein? 4/1/11

9/6/2011. Amino Acids. C α. Nonpolar, aliphatic R groups

Amino Acids. Review I: Protein Structure. Amino Acids: Structures. Amino Acids (contd.) Rajan Munshi

1. Describe the relationship of dietary protein and the health of major body systems.

Objective: You will be able to explain how the subcomponents of

1-To know what is protein 2-To identify Types of protein 3- To Know amino acids 4- To be differentiate between essential and nonessential amino acids

Fundamentals of Organic Chemistry CHEM 109 For Students of Health Colleges

If you like us, please share us on social media. The latest UCD Hyperlibrary newsletter is now complete, check it out.

Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Biological systems interact, and these systems and their interactions possess complex properties. STOP at enduring understanding 4A

Amino acids. Dr. Mamoun Ahram Summer semester,

AMINO ACIDS STRUCTURE, CLASSIFICATION, PROPERTIES. PRIMARY STRUCTURE OF PROTEINS

Properties of amino acids in proteins

Biochemistry - I. Prof. S. Dasgupta Department of Chemistry Indian Institute of Technology, Kharagpur Lecture 1 Amino Acids I

Biomolecules: amino acids

Introduction to proteins and protein structure

THE UNIVERSITY OF MANITOBA. DATE: Oct. 22, 2002 Midterm EXAMINATION. PAPER NO.: PAGE NO.: 1of 6 DEPARTMENT & COURSE NO.: 2.277/60.

Chemistry 121 Winter 17

Proteins are sometimes only produced in one cell type or cell compartment (brain has 15,000 expressed proteins, gut has 2,000).

Review II: The Molecules of Life

Distribution of the amino acids in Nature Frequency in proteins (%)

Chemical Nature of the Amino Acids. Table of a-amino Acids Found in Proteins

PHAR3316 Pharmacy biochemistry Exam #2 Fall 2010 KEY

Proteins and Amino Acids. Benjamin Caballero, MD, PhD Johns Hopkins University

Lipids: diverse group of hydrophobic molecules

Reactions and amino acids structure & properties

Amino acids-incorporated nanoflowers with an

Molecular Biology. general transfer: occurs normally in cells. special transfer: occurs only in the laboratory in specific conditions.

Macromolecules of Life -3 Amino Acids & Proteins

Judy Wieber. Department of Computational Biology. May 27, 2008

The Structure and Function of Large Biological Molecules Part 4: Proteins Chapter 5

Introduction to Proteomics Dr. Sanjeeva Srivastava Department of Biosciences and Bioengineering Indian Institute of Technology - Bombay

Chapter 3: Amino Acids and Peptides

Q1: Circle the best correct answer: (15 marks)

M1 - Renal, Fall 2007

Methionine (Met or M)

Amino acids. You are required to know and identify the 20 amino acids : their names, 3 letter abbreviations and their structures.

PROTEINS. Amino acids are the building blocks of proteins. Acid L-form * * Lecture 6 Macromolecules #2 O = N -C -C-O.

PROTEINS. Building blocks, structure and function. Aim: You will have a clear picture of protein construction and their general properties

PROTEIN. By: Shamsul Azahari Zainal Badari Department of Resource Management and Consumer Studies Faculty of Human Ecology UPM

The Structure and Function of Macromolecules

بسم هللا الرحمن الرحيم

Fatty acids and phospholipids

Biology. Lectures winter term st year of Pharmacy study

Glycolysis. Cellular Respiration

Lecture 11 AMINO ACIDS AND PROTEINS

Mutations and Disease Mutations in the Myosin Gene

Amino acids. Dr. Mamoun Ahram and Dr. Diala Abu-Hassan Summer semester,

Amino Acid Analyzer AAA400

Lecture 10 - Protein Turnover and Amino Acid Catabolism

AMINO ACIDS NON-ESSENTIAL ESSENTIAL

A Chemical Look at Proteins: Workhorses of the Cell

Introduction to Protein Structure Collection

CHM333 LECTURE 6: 1/25/12 SPRING 2012 Professor Christine Hrycyna AMINO ACIDS II: CLASSIFICATION AND CHEMICAL CHARACTERISTICS OF EACH AMINO ACID:

AP Bio. Protiens Chapter 5 1

E.coli Core Model: Metabolic Core

Macromolecules Structure and Function

Age-related reference ranges

Chapter 5: Structure and Function of Macromolecules AP Biology 2011

Biomolecules Amino Acids & Protein Chemistry

Short polymer. Dehydration removes a water molecule, forming a new bond. Longer polymer (a) Dehydration reaction in the synthesis of a polymer

Structure of proteins

CHAPTER 29 HW: AMINO ACIDS + PROTEINS

COO - l. H 3 N C a H l R 1

Low ds/dn Does Not Correlate With High Variation of Amino Acid Sequences Along the gp120 Protein Structure

Controlled biomimetic crystallization of ZIF-8 particles by amino acids

Cells. Variation and Function of Cells

0010 Amino Acids 40 Profile - Plasma

From sugar unit A From sugar unit B From sugar unit C

Towards a New Paradigm in Scientific Notation Patterns of Periodicity among Proteinogenic Amino Acids [Abridged Version]

Protein sequence alignment using binary string

(a) (i) Describe how the production and action of interferon differs from the production and action of lysozyme. (3)

Human Biochemistry Option B

0010 Amino Acid Analysis - 40 Plasma

I) Choose the best answer: 1- All of the following amino acids are neutral except: a) glycine. b) threonine. c) lysine. d) proline. e) leucine.

What Are Proteins? Lecture 9: Proteins. Proteins: large complex molecules composed of amino acids. Nutrition 150 Shallin Busch, Ph.D.

READ THIS FIRST. Your Name

Moorpark College Chemistry 11 Fall Instructor: Professor Gopal. Examination # 5: Section Five May 7, Name: (print)

2. Ionization Sources 3. Mass Analyzers 4. Tandem Mass Spectrometry

Amino Acids االحماض األمينية

Amino Acid Oxidation and the Urea Cycle

Biochemistry Prof. S. Dasgupta Department of Chemistry Indian Institute of Technology Kharagpur. Lecture -02 Amino Acids II

Student name ID # 2. (4 pts) What is the terminal electron acceptor in respiration? In photosynthesis?

استاذ الكيمياءالحيوية

For questions 1-4, match the carbohydrate with its size/functional group name:

The Conservation of Homochirality and Prebiotic Synthesis of Amino Acids

Maha AbuAjamieh. Tamara Wahbeh. Mamoon Ahram

Enzyme Catalytic Mechanisms. Dr. Kevin Ahern

Transcription:

Research Article imedpub Journals http://www.imedpub.com Colorectal Cancer: Open Access DOI: 10.21767/2471-9943.100005 Abstract Analysis of Cancer Proteins: Pattern Identification on Escherichia coli Species A major challenge of protein sequence analysis is efficient and accurate detection of pattern and similarities that allow functional prediction. We analyzed the different species of protein sequences for getting a pattern. In this work, we have analyzed to find pattern for cancer disease from Escherichia coli protein sequences. The Escherichia coli protein sequences have been compared with different species to find the pattern. This work may be used to find and design the accurate drug for cancer disease on human species. Received: October 01, ; Accepted: November 23, ; Published: November 30, Manikandakumar K 1, Srikumar R 2, Gokul Raj K 3 1 Department of Physics, Bharathidasan University Constituent College, Lalgudi 621 601, Tamil Nadu, India 2 Sree Lakshminaryana Institute of Medical Sciences, Villianur Commune, Kodapakkam, Pondicherry-605502, India 3 Department of Computer Science, T.V.K. Govt. Arts College, Thiruvarur 610 003, Tamil Nadu, Indian Corresponding author: ManikandaKumar K bioinfokm@gmail.com Introduction Human have battled against cancer throughout their existence. One of the first written descriptions of cancer is found in an Egyptian papyrus around 3000 B.C. A major challenge of protein sequence analysis is efficient and accurate detection of pattern and similarities that allow functional prediction. However, previous reports analyzed only a limited number of proteins Botos I, et al. [1] analyzed the catalytic domain of Escherichia coli in which they identified that Lon protease has a unique fold and a Ser-Lys dyad is in the active site. Eugene V et al. [2] analyzed the Sequence of similarity analysis of Escherichia coli proteins namely, Functional and evolutionary implications. Goldberg A L, et al. [3] analyzed the ATP-dependent protease La (lon) from Escherichia coli. Rasulova F S, et al. [4] analyzed the synthesis and characterisation of ATP-dependent forms of Lon-proteinase with modified N-terminal domain from Escherichia coli. Brunger AT [5] analyzed the free R value: A novel statistical quantity for assessing the accuracy of crystal structures. Botos I, et al. [6] analyzed the Atomic-resolution crystal structure of the proteolytic domain of Archaeoglobus fulgidus in which Lon reveals the conformational variability in the active sites of Lon proteases. Gottesman S and Maurizi M R [7] analyzed the regulation of proteolysis: Energydependent proteases and their targets. Engh R and Huber R [8] analyzed the accurate bond and angle parameters for X-ray protein-structure refinement. Manikandakumar K, et al. [9-15] analyzed for finding the patterns from different proteome and genome sequences. (Brunger A T, et al. [16] analyzed the crystallography and NMR system: A new software suite for macromolecular structure determination. Melnikov E, et al. [17] analyzed the coupling of proteolysis to ATP hydrolysis upon Escherichia coli Lon protease functioning of ATP hydrolysis. Department of Physics, Bharathidasan University Constituent College, Lalgudi 621 601, Tamil Nadu, India. Tel: :+91-431-2541100 Citation: Manikandakumar K, Srikumar R, Gokul Raj K. Analysis of Cancer Proteins: Pattern Identification on Escherichia coli Species. Colorec Cancer 2016, 1:1. Gottesman S, et al. [18] analyzed the protein quality control: Triage by chaperones and proteases. Botos I, et al. [19] analyzed the Crystal structure of the AAA+ α domain of E. coli Lon protease at 1.9 Å resolution. Brunger A T, et al. [20] analyzed the slowcooling protocols for crystallographic refinement by simulated annealing. In this work, we have analyzed to find pattern from Escherichia coli protein sequences. These sequences have been compared with different species to identify the pattern. Results and Discussion Analysis of individual amino acid contents: (Figure 1) We analyzed the amino acids of different species for Cancer disease (Table 1). From the 12 species, it is found that the E.coli has secured the alanine at highest level (7.87%). The lowest alanine at 6.36% in human species. In cysteine amino acid, the highest score secured is 2.23 in rat species. The least score for cysteine in E.coli species is at (1.37%). The E.coli species has secured at Under License of Creative Commons Attribution 3.0 License This article is available in: http://colorectal-cancer.imedpub.com/archive.php 1

high percentage of aspartic acid (6.59%). The least aspartic amino acid secured at (5.43%) in rat species. The rat species has secured at high percentage of glutamic amino acid (7.36%). The E.coli secured lowest glutamic amino acid (5.49%). The highest percentage of phenylalanine amino acid secured in horse species (4.23%). The lowest percentage of phenylalanine amino acid has secured in rat species (3.58%). The highest percentage of glycine amino acid is found in horse species (7.60%). The lowest percentage of glycine amino acid is found in rat species (6.37%). The highest percentage of histidine amino acid is found in E.coli species (3.73%). The lowest percentage of histidine amino acid is identified in cow species (2.46%). The highest percentage of isoleucine amino acid is detected in E.coli species (6.71%). The lowest percentage of isoleucine amino acid is found in rat species (4.41%). The highest percentage of lysine amino acid is identified in whale species (6.71%). The lowest percentage of lysine amino acid is detected in E.coli species (3.97%). The highest percentage of leucine amino acid is found in rat species (10.06%). The lowest percentage of leucine amino acid is identified in horse species (9.12%). The highest percentage of methionine amino acid is detected in E.coli species (2.81%). The lowest percentage of methionine amino acid is found in rat species (1.6%). The highest percentage of asparagine amino acid is identified in E.coli species (4.5%). The lowest percentage of asparagine amino acid is detected in whale species (3.63%). The highest percentage of proline amino acid is found in rat species (5.55%). The lowest percentage of proline amino acid is identified in whale species (4.78%). The highest percentage of glutamine amino acid is detected in E.coli and rat species (5.06%). The lowest percentage of glutamine amino acid is found in horse species (3.88%). The highest percentage of arginine amino acid is identified in human species (5.37%). The lowest percentage of arginine amino acid is detected in rat species (4.63%). The highest percentage of serine Figure 1 Analysis individual amino acid contents in different species. (X-axis: Name of the amino acid & Y-axis: percentage value). Table 1 Amino Acid calculation for different species in Cancer Disease. Name of the Species Name of the Amino Acid A C D E F G H I K L M N P Q R S T V W Y chimpanzee 6.95 1.82 5.63 6.5 3.88 7.07 2.69 5.11 5.84 9.26 2.2 4.07 5.07 4.41 5.08 6.55 5.68 7 1.5 3.67 cow 6.73 1.67 5.78 6.82 3.85 7.08 2.46 5.37 6.41 9.16 2.1 4.07 5.06 4.18 4.83 6.23 5.82 7.03 1.6 3.77 donkey 6.98 1.87 5.68 6.54 3.88 7.12 2.74 5.12 5.9 9.24 2.16 3.95 5.11 4.25 5.08 6.63 5.61 7.02 1.44 3.67 duck 7.01 1.78 5.66 6.59 3.88 7.05 2.69 5.36 5.96 9.35 2.25 4.02 4.9 4.12 5.08 6.95 5.68 6.81 1.41 3.45 ecoli 7.87 1.37 6.59 5.49 3.65 7.38 3.73 6.71 3.97 9.85 2.81 4.5 5.05 5.06 4.69 4.22 5.91 6.67 1.65 2.84 elephant 7.03 1.87 5.66 6.56 3.89 7.13 2.74 5.13 5.93 9.22 2.17 3.95 5.1 4.24 5.05 6.61 5.61 7.02 1.44 3.66 fish 7.39 1.71 5.75 6.47 4.04 7.18 2.84 5.32 5.98 9.22 2.14 4.22 4.99 4.09 4.9 6.41 5.47 6.9 1.38 3.61 horse 7.37 2.04 5.6 6.18 4.23 7.6 2.68 5.08 6.19 9.12 2.04 3.98 4.96 3.88 4.73 6.75 5.78 7.32 1.28 3.2 human 6.36 2 5.49 6.98 4.02 6.78 2.88 4.96 5.93 9.43 2.14 3.69 5.25 4.46 5.37 6.92 5.29 6.67 1.56 3.82 musmusculus 6.97 1.87 5.69 6.55 3.88 7.12 2.73 5.12 5.9 9.24 2.17 3.95 5.11 4.25 5.09 6.63 5.62 7.01 1.44 3.67 rat 6.86 2.23 5.43 7.36 3.58 6.37 2.84 4.41 5.83 10.06 1.6 3.78 5.55 5.06 4.63 6.9 4.43 6.86 1.88 4.34 whale 7.53 1.66 5.48 6.84 3.9 7.16 3.33 5.21 6.71 9.46 2.1 3.63 4.78 4.11 4.76 6.35 5.34 6.75 1.46 3.46 2 This article is available in: http://colorectal-cancer.imedpub.com/archive.php

amino acid is found in duck species (6.95%). The lowest percentage of serine amino acid is identified in E.coli species (4.22%). The highest percentage of threonine amino acid is detected in e.coli species (5.91%). The lowest percentage of threonine amino acid is found in rat species (4.43%). The highest percentage of valine amino acid is identified in horse species (7.32%). The lowest percentage of valine amino acid is detected in E.coli and human species (6.67%). The highest percentage of tryptophan amino acid is found in rat species (1.88%). The lowest percentage of tryptophan amino acid is identified in horse species (1.28%). The highest percentage of tyrosine amino acid is detected in rat species (4.34%). The lowest percentage of tyrosine amino acid is found in E.coli species (2.84%). Analysis of group of amino acid contents (Figure 2 and Table 2) The highest percentage of hydrophobic group amino acid species is idenfied in E.coli (23.23%). The lowest percentage of hydrophobic group amino acid species is detected in human Table 2 Analysis of group of amino acid contents. Proteins Hs Hw Puc Pc Cp Cn chimpanzee 21.37 18.1 27.78 9.68 10.92 12.13 cow 21.56 17.74 27.38 9.5 11.24 12.6 donkey 21.38 18.13 27.56 9.72 10.98 12.22 duck 21.52 18.04 27.82 9.33 11.04 12.25 ecoli 23.23 19.38 27.07 9.59 8.66 12.08 elephant 21.37 18.19 27.54 9.71 10.98 12.22 fish 21.44 18.56 27.37 9.54 10.88 12.22 horse 21.52 18.6 27.99 9.2 10.92 11.78 human 21.06 17.77 27.14 10.26 11.3 12.47 musmusculus 21.37 18.13 27.57 9.71 10.99 12.24 rat 21.33 17.59 26.54 11.29 10.46 12.79 whale 21.42 18.31 26.59 9.91 11.47 12.32 Hs Hydrophobic strong; Hw Hydrophobic weak; Puc Polar uncharged; Pc Polar charged; Cp Charged Positive; Cn Charged negative. (21.06%). The highest percentage of hydrophobic group amino acid species is found in E.coli (19.38%). The lowest percentage of hydrophobic group amino acid species is idenfied in rat (17.59%). The highest percentage of polar uncharged group amino acid species is detected in horse (27.99%). The lowest percentage of polar uncharged group amino acid species is found in rat (26.54%). The highest percentage of polar charged group amino acid species is identified in rat (11.29%). The lowest percentage of polar charged group amino acid species is detected in horse (9.2%). The highest percentage of charged positive group amino acid species is found in whale (11.47%). The lowest percentage of charged positive group amino acid species is identified in E.coli (8.66%). The E.coli species only has the least score of 8.66% when compared to other species. The other species has secured score greater than 10.46%. Therefore, the E.coli has the different pattern when compared with the other species. The highest percentage of charged negative group amino acid species is identified in rat (12.79%). The lowest percentage of charged negative group amino acid species is detected in horse (11.78%). Analysis of E.coli pattern from individual amino acid contents The E.coli secures the alanine and aspartic amino acid at 7.87% & 6.59% respectively. The other species has secured alanine and aspartic acid amino acid less than 7.56% & 5.78% respectively. The E.coli secures the glutamic amino acid at 5.49%. The other species has secured glutamic amino acid greater than 6.18%. The E.coli other amino acid like histidine, isoleucine, serine and threonine also secures either high or low percentage score when compared with other species. Therefore, it is found that the E.coli species is identifed with the different pattern compared with the other species individual amino acid contents. Analysis of E.coli pattern from group of amino acid contents: The E.coli secures the highest hydrophobic strong and hydrophobic Figure 2 Analysis for group of amino acid contents in different species. (X-axis: Name of the species & Y axis: percentage value). Under License of Creative Commons Attribution 3.0 License 3

weak amino acid group at 23.23% & 19.38% respectively when compared with other species. The other species has secured highest hydrophobic strong and hydrophobic weak amino acid group at less than 21.56% & 18.56% respectively. The E.coli species also secured the least score of 8.66% when compared with other species for charged positive amino acid group. The other species has secured greater than 10.46% for charged positive amino acid group. Therefore, it is found that the E.coli species is identified with the different pattern when compared with the other species. Conclusion We have analyzed different species of protein sequences. We identified a pattern on Escherichia coli protein sequences when compared with 12 different species. The Escherichia coli protein sequence only is getting a different pattern on analysis of individual amino acid contents and group of amino acid contents also. These results may be used to design a new accurate drug for cancer disease on human species. 4 This article is available in: http://colorectal-cancer.imedpub.com/archive.php

References 1 Botos I, Melnikov E E, Cherry S, Tropea J E, Khalatova A G, et al. (2004b) The catalytic domain of Escherichia coli Lon protease has a unique fold and a Ser-Lys dyad in the active site. J Biol Chem 279: 8140 8148. 2 Eugene V Koonin, Roman L Tatusov, Kenneth E Rudd (1995) Sequence similarity analysis of Escherichia coli proteins: Functional and evolutionary implications. Proc. Natl. Acad Sci 92: 11921-11925. 3 Goldberg A L, Moerschell R P, Chung C H, Maurizi M R (1994) ATPdependent protease La (lon) from Escherichia coli. Methods Enzymol 244: 350 375. 4 Rasulova F S, Dergousova N I, Melnikov E E, Ginodman L M, Rotanova T V (1998) Synthesis and characterisation of ATP-dependent forms of Lon-proteinase with modified N-terminal domain from Escherichia coli. Bioorg Khim 24: 370 375. 5 Brünger A T (1992) The free R value: A novel statistical quantity for assessing the accuracy of crystal structures. Nature 355: 472 474. 6 Botos I, Melnikov E E, Cherry S, Kozlov S, Makhovskaya O V, et al. (2005) Atomic-resolution crystal structure of the proteolytic domain of Archaeoglobus fulgidus Lon reveals the conformational variability in the active sites of Lon proteases. J Mol Biol 351: 144 157. 7 Gottesman S, Maurizi M R (1992) Regulation by proteolysis: Energydependent proteases and their targets. Microbiol Rev 56: 592 621. 8 Engh R, Huber R (1991) Accurate bond and angle parameters for X-ray protein-structure refinement. Acta Crystallogr 47: 392 400. 9 Manikandakumar K, Muthu Kumaran S, Srikumar R (2009a) Matrix Frequency Analysis of Oryza Sativa (japonica cultivar-group) Complete Genomes. Journal of Computer Science & Systems Biology 2: 159-166. 10 Manikandakumar K, Muthukumaran S, Srikumar R, Gokulraj K, Santhosh Baboo S (2009b) Analysis of Homo sapiens (Human) Chromosomes Complete Genome Using Matrix Frequency. nst Life Sciences and Bioinformatics 1: 57-66. 11 Manikandakumar K, Gokulraj K, Srikumar R, Muthu Kumaran S (2010a) Analysis of parity ratio of protein sequences: A new approach based on Chargaff s rule, Romanian Journal of Biophysics 20: 183-191. 12 Manikandakumar K, Gokulraj K, Srikumar R, Muthu Kumaran S (2010b) Matrix Frequency Analysis of Genome Sequences: Pattern Identification of Turfgrass Species. World Applied Sciences Journal 11: 315-320. 13 Manikandakumar K, Gokul Raj K, Srikumar R, Muthukumaran S (2010c) Classification of Protein Structural Classes using Isoluecine and Lysine Amino Acids. Journal of Proteomics and Bioinformatics 3: 221-229. 14 Manikandakumar K, Muthukumaran S, Srikumar R, Gokulraj K (2012a) Graphical Representation of Protein Sequences by CGR: Analysis of Pentagon and Hexagon Structures, Journal of Pharmacy Research 5: 514-518. 15 Manikandakumar K, Gokul Raj K, Muthukumaran S, Srikumar R (2012b) Secondary Structural Analysis of Families of Protein Sequences using Chaos Game Representation, Journal of Computer Science & Systems Biology 5: 047-051. 16 Brunger A T, Adams P D, Clore G M, DeLano W L, Gros P et al. (1998) Crystallography and NMR system: A new software suite for macromolecular structure determination. Acta Crystallogr. D Biol Crystallogr 54: 905 921. 17 Melnikov E E, Tsirulnikov K B, Rotanova T V (2000) Coupling of proteolysis to ATP hydrolysis upon Escherichia coli Lon protease functioning, I: Kinetic aspects of ATP hydrolysis. Bioorg Khim 26: 530 538. 18 Gottesman S, Wickner S, Maurizi M R (1997) Protein quality control: Triage by chaperones and proteases. Genes & Dev 11: 815 823. 19 Botos I, Melnikov E E, Cherry S, Khalatova A G, Rasulova F S, et al. (2004a) Crystal structure of the AAA+ α domain of E. coli Lon protease at 1.9 Å resolution. J Struct Biol 146: 113 122. 20 Brünger A T, Krukowski A, Erickson J W (1990) Slow-cooling protocols for crystallographic refinement by simulated annealing. Acta Crystallogr A 46: 585 593. Under License of Creative Commons Attribution 3.0 License 5