Investigating the effect of structural characteristics and residues composition on thermal adaptability of enzymes

A total of ۸۰ enzymes including ۴ kinds of enzymes (Adenylate kinase, Enolase, Citratesynthase and Malate dehydrogenase) belonging to ۴ temperature types of groups (psychrophilic,mesophilic, moderately thermophilic, and extremely thermophilic) were studied usingcomputational tools such as VADAR server [۱], ExPASy ProtParam tool [۲-۳],DiANNA(disulfide bonds prediction tool) [۴] and ProteinTools ( A Toolkit to Analyze ProteinStrucrures) [۵] to assess their ۳-D structural properties and amino acids preferences for differenttemperature adaptability of enzymes. Statistical analysis results, strongly suggested a regularincrease of molecular heaviness with an incremen in the temperature. More investigationshowed, small non-polar amino acids such as alanine and glycine in psychrophiles andmesophiles replaced by bulky ones such as Arginine, Lysine, Isoleucine, Lucien, and Valine inmoderate and extreme thermophiles. The bolder presence of arginine and lysine residues inthermophiles is confirmed by the high PI results obtained from ExPASy ProtParam analysis, andalso investigation in VADAR results showed that the average volume of amino acids inthermophiles is more than in psychrophilic ones, which is consistent with the statistical aminoacid composition that mentioned above. Investigation in parameters of Fraction of ChargedResidues (FCR) showed that thermophiles have more charged amino acids in comparisons toother groups, and also VADAR software confirmed and showed charged ASA increased in termsof frequency as the temperature increases.Salt bridges and hydrogen bonds were computed usingProteinTools and the results, showed that there is no significant difference between the ۴temperature types of enzymes.There was also a regular depletion of Disulfide bond with anincrease in the temperature.

کلیدواژه ها:

Thermal adaptability ، Physiochemical Properties ، ۳-D structural properties ، enzyme