Naturally Occurring Alkaline Amino Acids Function

Authors: Weina Li Sergey Fedosov Tianwei Tan Xuebing Xu Zheng Guo

Publish Date: 2014/03/29

Volume: 173, Issue: 1, Pages: 278-290

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Abstract

To maintain biological functions thousands of different reactions take place in human body at physiological pH 70 and mild conditions which is associated with health and disease Therefore to examine the catalytic function of the intrinsically occurring molecules such as amino acids at neutral pH is of fundamental interests Natural basic αamino acid of llysine larginine and lhistidine neutralized to physiological pH as salts were investigated for their ability to catalyze Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate Compared with their free base forms although neutralized alkaline amino acid salts reduced the catalytic activity markedly they were still capable to perform an efficient catalysis at physiological pH as porcine pancreatic lipase PPL one of the best enzymes that catalyze Knoevenagel condensation In agreement with the fact that the three basic amino acids were well neutralized stronger basic amino acid Arg and Lys showed more obvious variation in NH bend peak from the FTIR spectroscopy study Study of ethanol/water system and quantitative kinetic analysis suggested that the microenvironment in the vicinity of amino acid salts and protonability/deprotonability of the amine moiety may determine their catalytic activity and mechanism The kinetic study of best approximation suggested that the random binding might be the most probable catalytic mechanism for the neutralized alkaline amino acid saltcatalyzed Knoevenagel condensationThis work was supported by the National Basic Research Program of China 973 program 2013CB733600 and 2012CB725200 the National Nature Science Foundation of China 21390202 and 21106005 The support provided by China Scholarship Council No 2011688018 during a visit to Aarhus is also acknowledged

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