(1) Made by Lama nedal corrected by laith sorour

Transcription

1 sheet Biochem (1) Made by Lama nedal corrected by laith sorour

2 DATE :22/9/2016 *What is Amino Acid (a.a)? compound that contains both an amino group(-nh2) and a carboxyl group (- cooh) *composed of 1-alpha-carbon with hydrogen atom 2-alpha-amino group 3-alpha-carboxyl group 4-R-group * R-grouphydrated(H) (glycine) any other group *what is alpha amino acid? When the amino group attached to alpha-carbon *A.A can be written in zwitter form or simple form *what is the zwitter form? A molecule with both positive & negative charge *all protein (drived from A.A) are chiral and have at least one asymmetric chiral carbon except glycine is achiral Chiral asymmetrichave 4 different groups or atoms *if the R-group is H it is achiral NH3+(amino group +ve) a.a has 2 forms : 1-ionized coo- (carboxyl ve) zwitterion (a.a are more properly written in this form) 2-unionized (commonly written in this form) *alpha carbon in the center of a.a and chiral carbon *chiral A.A have 2 stereoisomers *Enantiomers : a stereoisomers that have mirror image *Enantiomers have *L-formmajority of A.A *D-form what is the natural form of stereoisomers (fischer projection formulas) for alanine L glyceraldehyde D * mostly cases D amino acids are toxic *D-form found and occur in antibiotics and bacterial cell walls (no D-form in human body) min 6.00 a.a (Alanine) (related to a.a position) L-form amino group on Left side D-form amino group on the right side

3 glyceraldehyde naturally found in D-form alanine naturally found in L form *hydroxyl group on right D\left L * amino group on left L\right D *carbohydrates in natural form are D-form *amino acids in natural form are L-form Classification of a.a min 7.47 ***************************************************************************** ***essential: BASIC( HIS\LYS) POLAR+UNCHARGED(THR) NON-POLAR(LEU\IIU\MET\VAL\PHE\TRP) ***non-essential: the rest A.A HIS\ARGSEMI-ESSENTIAL TOO\PARTIALLY FORMED *containing sulfurmet\cystiene(cys+cys)cystinedisulfide bond) *small a.agly\ala *glycine is the smallest one *sulfur containing a.a cys,met *aromatic a.a phe,trp,tyr *cyclic a.a proline(pro)has an imino group *branch chain a.a val,leu,ile *asparginaspartic acid *inic *glutaminglutamic acid *Tyr,Ser,Thr--hydroxyl group(enzyme activity\active site) *acidicasp\glu *basicarg\his\lys *19 a.a alpha amino group is primary\proline have a secondary amino group min essential a.a:- *found In food *body cant synthesis it *animal source origin *absence of one essential a.a can lead to disease *important for health & growth non-essential a.a :- *body can synthesis it *plant source origin *absence of one is not a big deal *A.A name shortcuts are either one letter (M) or 3 letters (met) abbreviations *19 a.a are chiral *1 a.a is achiral (glycine) *Aliphatic a.a have R group with hydrocarbon chain *Aromatic a.a have benzene ring in R-group *Ile\Thr contain a second chiral carbon **************************************************************************************** ***Uncommon a.a *found while protein synthesis *important for structural function *hydroxylysinhydroxyprolinfew connective tissue(c.t)collagen *synthesis hydroxylation *collagenconnective tissue(hydroxylysin\hydroxyprolin) to strength the collagen** need vitamin C

4 help in collagen synthesis *note: scurvy is a disease resulting from the lack of vitamin c which lead to lack of the collagen because the vitamin c is responsible for collagen synthesis *Thyroxin(T4)(hormone) found only in thyroid gland min *have 4 Iodin molecules * 90%<--iodinthyroxin *thyroxin drived from tyrosin(modified tyr) *thyroxin is important in metabolism *so when there is increase in thyroxin will happen a disease called thyroxyosis(leads to insomnia\weight loss) *hypothyroidism decreases in thyroxin which leads to increase in weight (urea cycle) min *end product of metabolism is urea *urea is waste product in protein synthesis *the one who found urea cycle is the same who found Krebs cycle *urea is not a.a because they don t have a carboxyl group so this is a uncommon a.a(modified a.a) A.A neurotransmitters 1)two A.A precursors for many neurotransmitters TrpSer *relaxation increase serotonin *depretion decrease serotonin Found in milk(make you sleepy) *tyramine wakes you up \ found in cheese slide 20 min 30 Phe (essential a.a) Tyr (non essential) *يعىط ي ف حالة الرعاش ح ى ت يتحول اىل L-dopa(drug) dopamine النه ال يستطيع اعبور حاجز الدموي للدماغ )blood brain barrier dopamine decrease in dopamine due to problems in brain(mid) substantia nigraleads to Parkinson diseasedopamine less than 50% epinephrine(adrenaline) neurotransmitter help in cardiac & respiratory output

5 norepinephrine(noradrenaline) hormone ***************************************************************************** titration of a.a min a.a have ve\+ve charges and can act as base\acid and can act as a buffer الرجوع للساليدات what is buffer? Solution that resists the change in ph when we add small amount of acid or base *ph=-log[h+] ph=pk +log (conjugate base\strong acid) *pka constant for amino acids each functional group example on buffer systems in human bodies **all buffer systems are found in blood min carbonic acid\bicarbonate (the most important) 60% of buffer capacity in human body found in : 1-respiratory system lungs respiratory buffer 2-kideymetabolic buffer system 2-amonia\ammonium found in kidney 3-protein buffer system 4-phosphoric acid buffer system phosphate + phosphoric acid found in kidney 5-hemoglobin buffer system (+\-)(acidic\basic) hemoglobin Isoelectric point = the ph at which the majority of molecules of a compound in solution have no net charge *peptide bond 2 a.a joined together to form peptide bond and release one water molecule 2 ends one end is N-terminal the other is C-terminal 1 a.a peptide (residue) <10oligopeptide 2 a.adipeptide >10polypeptide 3a.a tri peptide <200multiple polypeptide protein characteristic of peptide bond : *have double bond properties this means it have 2 resonance (2 hybrid) the hybrid consider C-N double bond character (short) and the rotation is restricted

6 you must write the peptide bond from NC Nalpha CarbonCarbonyl carbon example: *Serine(ser) + Alanine (Ala)Serylalanine(ser-ala) *Alanine(ala)+Serine(ser)Alanylserine (ala-ser) Min **Aspartam( Nutra Sweet)( Artificial Sweetner)zero caloriesphenylalanine *dangerous to people with phenylcatacoria *dipeptide **carnosine *found in muscle & brain tissue -dipeptide -b-alanine + histidine -detoxification at free radical -antioxidant properties -prolong cell life vitamin C,E,A *It has a number of antioxidant properties that may be beneficial. Carnosine has been proven to scavenge reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes formed from peroxidation of cell membrane fatty acids during oxidative stress **Glutathione *tripeptide γ glutamyl-l-cysteinylglycine 2e oxidation Glutathione(GSH)(reduced) Glutathione, GS-SG(oxidized)have a disulfide bond 2e reduction In pentose-phosphate pathway NADH forms *oxidative *reduced *free radicals= is an atom or group of atoms that have one or more unpaired electrons(incomplete oxidative),can have +ve,-ve or neutral charge. They are formed as necessary intermediates in a variety of normal biochemical reactions, but when generated in excess or not appropriately controlled, radicals can wreak havoc on a broad range of macromolecules. A prominent feature of radicals is that they have extremely high chemical reactivity, which explains not only their normal biological activities, but how they inflict damage on cells بنتتج بسبب العمليات الحيويه ي ف الخليه وبتتجمع ع ال cell wall و ي ه ال ي ل بتخ ي ل الخاليا يتقدنوا بالعمر وهيك مع الزمن تجمعها بخ ي ل الخليه تتقدم ي ف العمر مما يقودها للموت *phospholiration in electron transport system *glutathione transfer free radicals into water + oxygen molecule *free oxygen (in cell membrane)accumulationcell death **Enkephalinsnatural pain killer found in brain(leucine & methionine enkphalins) Oxytocin vs Vasopressin(ADH) *hormones *cyclic nanopeptide oxytocinisoleucine(at position 3) + leucine (at position 8) stimulate smooth muscle in the mammary gland during lactation vasopressinphenylalanin(3) + arginine (8)

7 *stimulate reabsorption of water by kidney thus raises blood pressure