Physico-chemical properties of the acid proteinase from A. fumigatus.

The physico-chemical properties of the purified acid proteinase were investigated. This enzyme was found to hydrolyze hemoglobin maximally among the different substrates used. The maximum hydrolysis of hemoglobin was found at pH 2.8 and 45 degrees C in 30 min. Km value of 5.5 X 10(-4) M was obtained from the Lineweaver Burk plot for the hydrolysis of hemoglobin. The enzyme was found to be most stable at pH 4.9. The maximum stability of the enzyme was observed with 2 per cent casein as a stabilising agent. It was found to have a molecular weight 37,500 consisting of 298 aminoacid residues. The partial specific volume of the acid proteinase was found to be 0.734 ml/g. Leucine and alanine were the amino and carboxy terminal aminoacids of the acid proteinase respectively.