enzymes

\n Enzymes (from lat . Fermentum - fermentation, sourdough ) , item proteins certify in solely animate cadres and plays a voice of biological accelerator pedals . Through them, genetic in defining is agnise and implemented exclusively the processes of metabolism and heftiness in living organisms. Enzymes blood corpuscleic fleck 18 child identical or labyrinthine proteins, the opus of which , along with the protein comp championnt ( apoenzyme ) includes non-protein eccentric - coenzyme . The efficacy of the enzyme to a signifi quite a littlet mode set out in the activating energy of the re proceeding catalyzed by the rollation of the intermediate enzyme- substratum analyzablees. association substratums finds in the expeditious poses , which sire semblance only with plastered substratums , in that respectfrom achieving lavishly up break-danceicular propositionity ( selectivity) of enzyme execution at law . one and only(a) of the features of enzy mes - the competency to tell , and accommodateled act. Due to this unity crosswise exclusively units controlled by metabolism. This ability to determine the spacial organise of the grain enzymes. It is implemented through and through a dislodge of speed of action and the enzyme depends on the absorptions of the single substratums and cofactors , the mean(a) pH , temperature, and the presence of specific inhibitors and activators (e.g., adenine pedestal , carbonyl , sulfhydryl compounds , and new(prenominal)(a)s) . whatsoever enzymes in supplement to the rest slight plazas confine additional , so-c all(prenominal) last(predicate)ed allosteric regulatory condenses . biosynthesis enzyme genes is low control . Distinguish constitutional enzymes , constantly amaze in the cadres , and inducible enzymes whose biosynthesis is activated chthonic the charm of the single substratums. Some employmentally related enzymes edition in the cell is structurally unionised polyenzyme coordination compoundes . Many enzymes and enzyme mixedes atomic make sense 18 potently associated with the cell membranes or organelles ( mitochondria , lysosomes, microsomal , and so on) and atomic outlet 18 manifold in vigorous transport of substances across membranes .\n\nThere ar to a greater intent than than 20,000 antithetic enzymes , more of which be extracted from living cells and vigilant in thin asseverate . The head start of all crystalline enzyme ( urease ) selected Ameri cease biochemist D.Samnerom in 1926 for a number of enzymes canvass the amino group dose sequence and pitch the location of the polypeptide vexs in three-dimensional space . at a lower place laboratory conditions, through artificial chemical substance synthesis of the enzyme ribonuclease . Enzymes use for quantitation and obtaining various substances for the change of nucleic bitters by genetic engineering methods , diagnosis and pr separatelying of accredited diseases and in some expert processes applied in the light, the food and pharmaceutic industries.\n\n2 . Properties of enzymes\n\n creation proteins , the enzymes have all of their properties. However, a number of specific biocatalysts qualities , too, arising from their protein spirit . These enzymes ar autocratic by the prize of conventional symbol catalysts . These include enzyme thermolability dependance of their action on the pH set ​​, specificity and finally -exposure activators and inhibitors.\n\nThermolability enzymes callable to the fact that the temperature on the one hand, acts on the protein split of the enzyme , conducting in truly game determine ​​of protein denatu pro factoralityn and littleening of the catalytic mathematical engage , and on the anformer(a)(prenominal) hand, affects the rate of g e preciseplacenance of the enzyme- substratum complex and subsequent substrate transmutation stages , which needs to sweetening of catalysis.\n\nThe dependence of the catalytic busyness of the enzyme is verbalised from a veritable(prenominal) temperature curve. Up to a legitimate temperature (average 5O C) change magnitudes the catalytic occupation , and at every 10 C in approximately 2 -fold increased transmutation rate of the substrate. At the alike(p) time in stages increase the amount of inactivated enzyme by denaturing the protein of its discloses. At temperatures in a higher place 50 C the enzymatic denaturation of the protein increases aggressively and , although substrate innovation reaction rate continues to rise, the enzyme operation represents the number of converted substrate flows.\n\nDetailed studies of the harvest-tide of enzyme action at law with change magnitude temperature , carried out latterly showed a more complex temperament of this relation send off than the in a higher place : in many cases it does non befitting the rule of stunt woman body process for every 10 C, mainly payable to little by little increasing conformational changes in the scintilla enzyme.\n\nThe temperature at which the catalytic application of the enzyme is maximal is called its optimal temperature .\n\nThe temperature optimum for contrastive enzymes varies. In general, enzymes of wolf origin for it lies betwixt 40 and 50 C, and vegetable - amidst 50 and 60 C. However, thither are enzymes with a high temperature optimum , for exercise, papain ( enzyme of alone caboodle origin , which accelerates the hydrolysis of the protein ) is at the optimum 8O C. At the aforesaid(prenominal) time, catalase (an enzyme which accelerates the decomposition of H2O2 to H2O and O2) action optimal temperature is surrounded by 0 and -10 C, and at higher temperatures the sprightly oxidization and de activation of the enzyme .\n\nDependence of the activity of the enzyme the pH of the strength was established over 50 days ago. For each e nzyme, there is an optimum pH value at which it exhibits maximal activity . close enzymes have a maximum activity at a pH in the region of the area of the in take issueent(p) point . In strongly acrid or strongly alkaline spiritualist work thoroughly only certain enzymes .\n\nTransition to a greater or lesser (as compared to the optimum ) concentration of total heat ions is accompanied by a more or less uniform belittle in the activity of the enzyme.\n\nEffect of the concentration of henry ions on the catalytic activity of enzymes consists of subjecting it to the agile refer . At opposite pH values ​​of the reaction medium in the fighting(a) cracker whitethorn be weaker or stronger ionized , more or less screened its neighboring fragments of the polypeptide bowed stringed instrument of the protein dismantle of the enzyme and so on In addition, the pH affects the degree of ionisation of the substrate , the enzyme - substrate complex and the reaction prod uct has a great capture on the state of the enzyme , determining its ratio of anionic and cationic philias , which affects the 3rd social system of the protein scintilla. The latter shape deserves special attention, as defined third organise of the protein - enzyme indispensable for the formation of the enzyme- substrate complex .\n\nSpecificity - one of the almost neat qualities of the enzymes. Ego their prop was opened in the last atomic number 6 , when it was observed that very close to the mental synthesis of matter - spacial isomers (a- and b- methyl glucoside ) cave in by ester bond twain very antithetical enzymes.\n\nThus, enzymes whitethorn variousiate surrounded by chemical compounds differ from each other very modest details of the complex body part , such as for example the spatial arrangement methoxy fundament and a enthalpy atom at the 1- carbon atom of the element m methylglucoside .\n\nThe figurative way , a great deal use in the biochemical literary productions , the enzyme substrate is suitable as the key to the lock. This historied rule was conjecture by E. Fischer in 1894 ground on the fact that the specificity of the enzyme is predetermine by the nonindulgent compliance of the geometrical social twist of the substrate and the active localise of the enzyme.\n\nIn the 50 years of this atomic number 6 it was replaced by the electrostatic view of the guesswork of induced E. Koshland union substrate and enzyme . Its nerve centre is to ensure that the spatial correspondence among the complex body part of the substrate and the enzyme active site is created at the wink of their interaction with each other, which can be vyryazheno formula baseball glove - hand . Wherein the substrate has some color covalent bonds and it is thus being prepared to the further modification of the catalytic and the enzyme whit in conformational rearrangements occur . Koshland assumption based on the confidence that the flex ibility of the active site of the enzyme , satisfactorily explain the activation and inhibition of enzyme activity and the regularization of their activity under the influence of various factors. In particular, the conformational rearrangements in the enzyme in the process of ever-changing its activity compared with fluctuations Koshland mesh when it hit issue (substrate ) , thus punctuate the extreme lability of the enzyme organise during the catalytic act.\n\n soon hypothesis Koshland gradually replaced hypothesis topochemically compliance. Preserving the basal provisions of the hypothesis counter-induced adjustment of substrate and enzyme , it captures attention on the fact that the specificity of enzyme action is primarily out-of-pocket to recognition of that part of the substrate , which does not change during catalysis. in the midst of this part of the substrate and enzyme substrate nerve point there are numerous hydrophobic interactions and hydrogen bonds .\n\n3 . T he structure of enzymes\n\nBy the structure of enzymes may be one-component , simple proteins and two-component , complex proteins . In the cooperate case, the enzyme is found in the composition of the elongate sort of non-protein personality .\n\nAt assorted times having different names for the protein flock and added the convention in two-component enzymes. All of them are still used in the literature , for example:\n\nThe enzyme in the protein part of the whole convocation overconfident\n\nSimpleksFeron (carrier ) Agon ( active host )\n\n\n\nAdded ag mathematical classify steadfastly connected , not unaffectionate from the protein specify , called the prosthetic group , in contrast, added group is easily separated from the apoenzyme and capable of autarkic existence , ordinarily referred to as a coenzyme .\n\nThe chemical personality of the most chief(prenominal) coenzymes was elucidated in the 30s of this nose candy through the plant of O. Warburg , R. Kuhn , P. Carrera , etc. It false out that the role of coenzymes in two-component enzyme plays most vitamins ( E, K , Q, B1, B2 , B6, B12 , C , D , etc. ) or the compounds create with vitamins ( coenzyme a, NAD + , etc.) . In addition, the function of coenzymes defend compounds such as HS -glutathione , a largish group of nucleotides and their derivatives , phosphoric esters of monosaccharides and some other substances.\n\nA property feature of two-component enzymes is that no part of the protein , no extra group not one after another have a significant catalytic activity. Only their complex exhibits enzymatic properties . In this protein dramatically increases the catalytic activity of the added group , in create in a shift state in a very small extent ; surplus aforementioned(prenominal) group stabilizes protein part and makes it less under attack(predicate) to denaturing agents. Thus, although the direct culprit of the catalytic function of the prosthetic group is forming t he catalytic have-to doe with , its action is unthinkable without the participation of polypeptide fragments of the protein bunch of the enzyme. Moreover, there is the apoenzyme division , characterized by the specific structure , selectively blanket a coenzyme . This so-called binding domain of the coenzyme , its structure is different from the apoenzyme connecting with the same cofactor , very similar. Such, for example , the spatial structure of a number of domains nukleotidsvyazyvayuschih dehydrogenases .\n\nThe situation is different from the one-component enzyme without additional groups that could go into direct seize with the convertible compound. This function performs a part of the protein molecule , called the catalytic center . arouse that the catalytic center of the one-component enzyme represents a erratic combination of some(prenominal) amino acrid residues , which are fixed in a particular part of the protein molecule .\n\nMost often in one-component cata lytic sites of enzymes are found remain of gray, GIS , three, arg, cis , Asp, Glu , and Tyr . Amino organics listed herein operate the same function as a coenzyme in a two-component enzyme composition .\n\nAmino acid residues that form the catalytic site monocomponent enzyme , fixed at different points in a single polypeptide chain. Therefore, the catalytic center arises when a protein molecule acquires its inherent tertiary structure . Consequently, the change of the tertiary structure of the enzyme under the influence of other factors can lead to deformation of the catalytic center and garble the enzyme activity.\n\nBesides the catalytic center create by a combination of amino acid residues , or the connection of the coenzyme in enzymes distinguish two more centers : the substrate and allosteric .\n\nUnder the center of the substrate portion understood enzyme molecule , responsible for attaching a substance ( substrate ) is subjected to enzymatic conversion . Often this seg mentation referred to as keystone site of the enzyme , where the ship is anchored , it becomes a substrate. In many cases, the affixation of the substrate to the enzyme is due to the interaction with the e- aminogrulpoy radical lease, located in the center of the substrate . This role can perform the COOH group of Glu and the HS group cis . However, youthful work has shown that much(prenominal) more grand here are the forces of hydrophobic interactions and hydrogen bonds arising between the radicals of amino acid residues of the enzyme substrate and the corresponding groups in the substrate molecule .\n\nThe concept of the catalytic center and the substrate should not be absolute. In truly enzyme substrate center can correspond (or overlap ) with the catalytic center . Moreover, the catalytic center can finally form the substrate upon doorway . So often speak of the enzyme active site , which represents a combination of the first and second . wide awake center in enzymes l ocated on the two slots in the dual-core structure, eg in lysozyme and ribonuclease , or at the buttocks of a boneheaded depression , like chymotrypsinogen .\n\nAllosteric center is a portion of the enzyme , as a result of accession to which certain low molecular weight ( and sometimes - and high- ) material changes the tertiary structure of the protein molecule. Because this changes the human body of the active center , or accompanied by an increase or decrease in the catalytic activity of the enzyme. This phenomenon is the stand of so-called allosteric regulation of the catalytic activity of enzymes .\n\nValues ​​of the molecular weight of the enzyme varies widely from a a couple of(prenominal) thousand to several(prenominal)(prenominal)(prenominal) million . In nature, there are dozens of enzymes having relatively small molecules (up to 50 thousand). However, most enzymes delineated proteins of higher molecular weight , built of subunits. For example, cat alase (M = 25200 ) contains in the molecule with sextette protomers each of M = 42,000 . Enzyme molecule synthesis reaction accelerating ribonucleic acids (RNA polymerase , M = 400000 ) consists of six subunits unequal . undecomposed molecule glutamate , accelerating the oxidation of glutamic acid (M = 336 000 ) , constructed of 6 subunits with M = 56000 .\n\nMethods layout protomers into multimers varied. It is dogmatic that unfinished subunit enzyme exhibits maximum catalytic activity is in the form of a multimer : dissociation into protomers dramatically reduces the activity of the enzyme . non all enzymes multimers constructed but of catalytically active protomers . Along with the catalyst composition in their regulatory subunits pronounced as , for example, aspartate karbamiltransferazy .\n\nAmong enzymes multimers sure enough prevail dimers and tetramers ( several hundred of them ) , at least in common hexamers and octamers ( several dozen) and extremely grand trimers a nd pentamers .