Amylases amino acid composition

Thermophilic archaeal a-amylases do not differ superficially from other a-amylases in their molecular size and amino acid composition. They are primarily monomeric enzymes with molecular weights of 40-70 kDa.84,88-90 Some of these amylases produce specific maltodextrin products, which are also summarized in Table 7.1. 

The amino acid compositions of the alpha-amylase from human saliva, hog pancreas, Bacillus suhtilfs, B. stearothermo-philus, Aspergillus oryzae, and malted sorghum have been determined and are shown in Table III. The results show that alpha-amylases from these different sources differ widely in structure. In particular, it is to be noted that cystine and cysteine were not found in the alpha-amylase from B. subtilis. The sequence of amino acids or the three-dimensional structure of any one alpha-amylase is not yet known. The enzyme from A. oryzae differs from the others further, because it is a glycoprotein containing a small proportion of carbo-hydrate. ... 

Amino Acid Composition of alpfco-Amylases from Different Sources"... 

The amino acid compositions of the beta-amylase from sweet potato, soya bean, wheat, and malted sorghum have been determined, and are shown in Table XIII. These results may suggest that the beta-amylase from these different sources differs in structure. This is, perhaps, not surprising, but it should be noted that the sorghum amylase contained 9% of pentose, and the important, sulfiir-containing amino acid cysteine was not reported and the soya-bean enzyme still contained traces of aipba-amylase and phosphatase. The sequence of amino acids, or the three-dimensional structure of any... 

The acid-stable a-amylase of Aspergillus niger and the acid-labile a-amylase of A. oryzae have been studied.It was shown that in addition to the more stable acid-resistant properties, the a-amylase of A. niger possesses increased thermal stability in comparison with the a-amylase of A. oryzae. The molecular weight of the acid-stable a-amylase is 5.8 x 10 The amino-acid composition, as well as the C- and A -terminal amino-acids of both forms of a-amylases were determined. It was shown that the enzymes each contain one thiol group, which, being bound to Ca ", plays an important role in maintaining the catalytically active conformation of the enzyme. 

The results of Philpot and Small (8) are strong evidrace that lyrodne can be diazotized. However, it would appear that careful studies ate called for to determine just what other grouping) may react. Spectro-photometric examination of a number of treated protdns whose amino acid composition is known should prove interesting. In this connection, it should be recalled that Philpot and Small found tiiat in diazotized pepsin there was an absorption at 411,5 m/t, attributable to the diazo structure. This fact has been used by Li et al. (312), in their studies of nitrous acid cn hormones and by Little and Caldw (186), who compared the rates of inactivation of pancreatic amylase by nitrous add and of diazotization of tyrosine. 

Ovine pancreatic a-amylase has been purified by fractional precipitation, ion-exchange chromatography, and specific adsorption onto Sephadex. The enzyme was obtained as a homogeneous glycoprotein, which was shown, by various physicochemical criteria, to exist as a single species. The properties and amino-acid composition of the enzyme (mol. wt. 5.6—5.8 x 10, p/3.2) were compared with those of porcine pancreatic a-amylase. 

The a-amylases from five strains of Bacillus amyloliquefaciens have been compared to determine whether differences in primary structure are responsible for variations in catalytic properties among the enzymes. Amino-acid analysis established virtually identical compositions for the proteins reaction with... 

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