Functions of Enzymes in Metabolic Reaction

Functions of Enzymes in Metabolic ReactionEnzymes work a fundamental role in either metabolic reaction that occurs in each(prenominal) living organisms. Enzymes be proteins which has the ability to bind to substratums and break substrate into products. In most cases, enzymes act as catalyst as they tutelage the reactants to come closer by use their active sites. In this seek I will be reviewing the structure and function of a serine proteinase known as subtilisin and I will analyze the contrastive techniques utilise by different researchers to define the structure or functions of Subtilisin.Subtilisin is tack in various forms such as Carlsberg and BNP. All three enzymes atomic number 18 from different origins, but they prevail similar primary structure although, their tertiary structures be completely different. Subtilisin BPN is an extracellular peptidase enzyme of a spore forming organism Bacullus Amyloliquelaniens. This enzyme contains a undivided peptide scop e of amino acid containing 275 residues with no disulphide bridges or SH group. The subtilisin BNP contains 8 right handed helical segment these regions are (Alden et al, 1970). Many aberrance has been observed due to the standard helix. The longest helix contains a subdue of residues such as Ala 223 to Histidine 238 which runs all the way from the top of the molecule legal opinion the molecules and to the other end. The other 6 helical segments lie approximately repeat to the longest helix (Alden et al, 1970).Subtilisins are example of serine protease these are found in every organism that exists. There are several examples of serine protease enzyme and one of them is alpha-Chymotrypsin which is one of the known enzymes in the Trypsin family. The Trypsin and the subtilisin are believed to have create by mental actd as they have similar mechanism of action even though they are non detectably related. Subtilisin is a bacterial protease, however Trypsin including -Chymotrypsin , Trypsin and Elastase re from mammalian origin. These are the known enzymes to have evolved convergent because they have similar active sites and catalytic mechanisms but has no similarities in terms of sequence or conformational homology. The ii known types of subtilisin are BNP and Carlsberg twain have similar polypeptide chain, but at that place are segments on the chain where a number of residues has either been replaced or deleted. According to Emil (1966), BPN consist of peptide chain of 275 amino acids residues, however Carlsberg enzyme contains only 274 amino acid residues. As mentioned in this paper, the chain is only different by 83 residues which may lead to the question why they are different .Furthermore, the similarities and differences between BNP and Carlsberg insinuate there have been deletions which have caused both of these enzymes to evolve in different ways. These enzymes are believed to be serine protease enzymes which mover they all originate from the sa me source and due to evolution these enzyme has been converging onward from each others path and both enzyme adapted in its environment in order to survive. This resulted subtilisin to be present in bacteria and -Chymotrypsin is found in the mammalian pancreas. This now brings us to the point that -Chymotrypsin and Subtilisins having the same catalytic mechanisms. This suggest that both Trypsin family and subtilisin family originates from source.Serine proteases are highly circumstantial enzymes as they use His, Ser and asp part of their active site. The main lineament of a serine protease is that they have a unique Ser residue of exceptional reactivity that forms a covalent bond with some(a) of the substrates or inhibitors (Creighton J). In both Trypsin and subtilisin shows many affinity and both contains the particularly highly reaction serine residue which can be specifically phosphorylated by other substrate such as isoprophylfluorophosphate (Alden and Wright, 1970), sulpho nated and acylated using different enzymes. Further, research was carried out to find out the protonotic equilibria exhibited by both of these enzymes.The enzymatic similarity between the cardinal different serine protease could be the involvement of a Histidine residue as it has been mentioned in most literature. previous(prenominal) studies suggested that tertiary structure of -Chymotrypsin and subtilisin contains hydrogen bonding involvement in the Enzyme-substrate Byzantine (Polgar and Bender, 1969). The Kcat for hydrolysis of p-nitrophenyl acetate by BPN depends on a group with a pK of 7.2, which presumptively was Histidine (Alden and Wright, 1970).Studies were carried out to determine the structure of the enzymes by Neidhart et al (1988) and they successfully groovy the structure of Carlsberg. The structure was refines at 2.5 resolution using X-ray crystallography. Wright et all (1969) found out that subtilisin BNP possesses the catalytic triad, emplacement of active si te including Aspartate, Histidine, and serine residues characteristic of the Trypsin family. Further study carried out by Robertus et al (1972), demonstrated that the arrangement and characteristics of the active site is akin for both BPN and other member of the Trypsin family, which means the peptide around the active site were highly conserved. In contrast, the overall peptide chain folding of subtilisin BPN reassembles those in the Trypsin family. Thus the relationship between BPN and mammalian Trypsin family of enzymes have been classified as a case of convergent evolution (Robertus et all, 1972). The catalytic triad consist of the residue Asp 32, His 64 and Ser 221. This supports the charge pass hypothesis and the catalytic triad is the most important part of the serine protease as it helps the enzymes to work effectively. Subtilisin also contains calcium binding loops which contains abut 75-81 residues which is identical in both type of subtilisin (Neidhart et al, 1988).Subt ilisin and Chymotrypsin both are highly specific as they only bind to specific substrates. For example, proflovin is a good hawkish inhibitor for Chymotrypsin is inefficient against subtilisin. And oppositely subtilisin has a good competitive inhibitor 4-(4aminophenylaze)-phenylarsonic acid, where as it doesnt move with Chymotrypsin at all (Alden et al, 1970). Despite the Histidine residue in the active site, some specific inhibitors still bind to the active site by acylation of the Histidine of the Chymotrypsin however they do not react with subtilisin. There are differences between subtilisin and Trypsin subtilisin does not contain any disulphide bridges, but Chymotrypsin has five and Trypsin has 6 which suggest that trypsins are more cystine rich. So apart from the surrounding area of the serine 221 in subtilisin, these two classes have no resemblance from each other as cold as the primary sequence is concern (Alden et al, 1970).