Gas chromatographic analysis of amino acids from the action of proteolytic enzymes on soil humic acids

Six proteases released more amino compounds from albumin than from a humic acid. Pronase and thermolysin released about one-sixth of the acid-hydrolysable amino acids from a humic acid, papain had slight activity while chymotrypsin, trypsin and subtilopeptidase did not attack humic acid. Thermolysin hydrolysates of four humic acids contained peptides which on acid hydrolysis broke down to increase three fold the yield of α-amino N. Net amounts of amino compounds released on incubation of thermolysin and humic acids were directly related to incubation time, substrate concentration and enzyme concentration.