Википедија

Transaminaza — разлика између измена

Интерактиван преглед историје
Новија измена →
Садржај обрисан Садржај додат
ВизуелноВикитекст
.
 
.
Ред 1:
[[Датотека:Transaminierung.svg|thumb|right|300px|Reakcija aminotransfera između [[aminokiselina|aminokiseline]] i [[Ketokiselina|alfa-ketokiseline]]. Amino (<chem>NH2</chem>) grupa i keto (<chem>=O</chem>) grupa se razmenjuju.]]
[[Датотека:Aspartate transaminase.png|thumb|right|300px|[[Aspartatna transaminaza]]<ref>{{cite journal | title = Chicken heart soluble aspartate aminotransferase. Purification and properties |author1=Bertland, L.H. |author2=Kaplan, N.O. |lastauthoramp=yes |journal = Biochemistry |date = 1968 |volume = 7 |pages = 134-142 |pmid = 5758538}}</ref><ref>{{cite journal | title = Amino acid metabolism in plants. III. Purification and some properties of a multispecific aminotransferase isolated from bushbean seedlings (''Phaseolus vulgaris'' L.) |author1=Forest, J.C. |author2=Wightman, F. |lastauthoramp=yes |journal = Can. J. Biochem. |date = 1973 |volume = 50 |pages = 813-829 |pmid = }}</ref><ref>{{cite journal | title = Kinetic studies of glutamic oxaloacetic transaminase isozymes |author1=Henson, C.P. |author2=Cleland, W.W. |lastauthoramp=yes |journal = Biochemistry |date = 1964 |volume = 3 |pages = 338-345 |pmid = 14155095}}</ref><ref>{{cite journal | title = The concentration of aspartate aminotransferase from brewers&#8217; yeast |author = Schreiber, G. |author2 = Eckstein, M. |author3 = Oeser, A. |author4 = Holzer, H. |journal = Biochem. Z. |date = 1964 |volume = 340 |pages = 13-20 |pmid = 14317947}}</ref><ref>{{cite journal | title = Evidence of phenylalanine transaminase activity in the isoenzymes of aspartate transaminase |author1=Shrawder, E. |author2=Martinez-Carrion, M. |lastauthoramp=yes |journal = J. Biol. Chem. |date = 1972 |volume = 247 |pages = 2486-2492 |pmid = 4623131}}</ref> iz -{''[[E. coli]]''}- sa Piridoksal 5' fosfatnim kofaktorom]]
 
{{rut}}
'''Transaminaze''' ili '''aminotransferaze''' su [[enzim]]i koji [[kataliza|katalizuju]] reakciju [[transaminacija|transaminacije]] između [[aminokiselina]] i [[Ketokiselina|&alpha;-ketokiselina]]. Oni su važni za sintezu aminokiselina, iz kojih se formiraju proteini.<ref>{{cite journal | title = Transamination. Part I. The isolation of the apoenzyme of glutamic-aspartic transaminase from pig heart muscle |author1=Banks, B.E.C. |author2=Vernon, C.A. |lastauthoramp=yes |journal = J. Chem. Soc. (Lond.) |date = 1961 |volume = |pages = 1698-1705 |pmid = }}</ref>
 
== Funkcija i mehanizam ==
 
Aminokiselina sadrži [[amin]]o (<chem>NH2</chem>) grupu. Keto kiselina sadrži [[keton|keto]] (<chem>=O</chem>) group. InU [[transamination|transaminaciji]], the <chem>NH2</chem> groupgrupa onsa onejednog moleculemolekula isse exchangedzamenjuje with thesa <chem>=O</chem> groupgrupom ondrugog the other moleculemolekula. TheAminokiselina aminopostaje acid becomes a keto acidketokiselina, and the keto acid becomesi anketokiselina aminopostaje acidaminokiselina.<ref>{{cite journal | title = Glutamic aspartic transaminase. I. Assay, purification, and general properties |author = Jenkins, W.T. |author2 = Yphantis, D.A. |author3 = Sizer, I.W. |journal = J. Biol. Chem. |date = 1959 |volume = 234 |pages = 51-57 |pmid = 13610891}}</ref><ref>{{cite journal | title = Aspartate: 2-oxoglutarate aminotransferase from ''Trichomonas vaginalis''. Identity of aspartate aminotransferase and aromatic amino acid aminotransferase |author1=Lowe, P.N. |author2=Rowe, A.F. |lastauthoramp=yes |journal = Biochem. J. |date = 1985 |volume = 232 |pages = 689-695 |pmid = 3879173}}</ref><ref>{{cite journal | title = Multispecific aspartate and aromatic amino acid aminotransferases in ''Escherichia coli'' |author1=Mavrides, C. |author2=Orr, W. |lastauthoramp=yes |journal = J. Biol. Chem. |date = 1975 |volume = 250 |pages = 4128-4133 |pmid = 236311}}</ref>
 
MostVećina transaminasestransaminaza aresu [[protein]]ski enzymesenzimi. HoweverMeđutim, someza transaminationneke activitiestransaminacione of theaktivnosti [[ribosomeribozom]]a haveje beenutvrđeno foundda tosu be catalyzed bykatalizovane [[ribozymesribozim]]ima (RNARNK enzymesenzimima). ExamplesPrimeri beingtoga thesu [[hammerhead ribozyme|hamerhed ribozim]], the [[VS ribozyme|VS ribozim]] and thei [[hairpin ribozyme|ukosnični ribozim]].
 
Za dejstvo transaminaza je neophodan koenzim [[piridoksal-fosfat]], koji se konvertuje u [[piridoksamin]] u prvoj fazi reakcije, kad se aminokiselina konvertuje u ketokiselinu. [[Piridoksamin]] vezan za enzime reaguje sa [[piruvat]]om, [[oksaloacetat]]om, ili [[alfa-Ketoglutarna kiselina|alfa-ketoglutaratom]], pri čemu se formira [[alanin]], [[aspartična kiselina]], ili [[glutaminska kiselina]], respektivno. Mnoge reakcije transaminacije se odvijaju u tkivima posredstvom transaminaze specifične za dati amino/ketokiselinski par. Reakcije su lako reverzibilne, a smer je određen viškom prisutnog reaktanta. Specifični enzimi su imenovani po jednom od reaktanata para, npr. reakcija između glutaminske kiseline i piruvinske kiseline kojom se formira [[alfa-ketoglutarna kiselina]] i alanin je posredovana [[Alanin transaminaza|glutaminsko-piruvinskom transaminazom]] ili GPT skraćeno.
Transaminases require the coenzyme [[pyridoxal-phosphate]], which is converted into [[pyridoxamine]] in the first phase of the reaction, when an amino acid is converted into a keto acid. Enzyme-bound [[pyridoxamine]] in turn reacts with [[pyruvate]], [[oxaloacetate]], or [[alpha-ketoglutarate]], giving [[alanine]], [[aspartic acid]], or [[glutamic acid]], respectively. Many transamination reactions occur in tissues, catalysed by transaminases specific for a particular amino/keto acid pair. The reactions are readily reversible, the direction being determined by which of the reactants are in excess. The specific enzymes are named from one of the reactant pairs, for example; the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called glutamic-pyruvic transaminase or GPT for short.
 
Aktivnosti tkivne transaminaze se mogu ispitati putem inkubacije homogenata sa raznim amino/keto parovima kiselina. Transaminacija je demonstrirana ako se korespondirajuća nova aminokiseline i ketokiselina formiraju, što se može odrediti hromatografijom na papiru. Reverzibilnost se demonstrira koristeći komplementarni par keto/aminokiseline kao početne reakctante.
Tissue transaminase activities can be investigated by incubating a [[wiktionary:homogenate|homogenate]] with various amino/keto acid pairs. Transamination is demonstrated if the corresponding new amino acid and keto acid are formed, as revealed by paper chromatography. Reversibility is demonstrated by using the complementary keto/amino acid pair as starting reactants. After chromatogram has been taken out of the solvent the chromatogram is then treated with [[ninhydrin]] to locate the spots.
 
== Vidi još ==
* [[ValproicValproinska acidkiselina]] - ainhibitor [[4-Aminobutyrate aminotransferase|GABA transaminasetransaminaze]] inhibitor
 
== Reference ==
{{Reflist|30em}}
 
== Literatura ==
Преузето из „https://sr.wikipedia.org/wiki/Transaminaza”