Thiol-Dependent Serine Proteinase from Paecilomyces lilacinus: Purification and Catalytic Properties

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E. K. Kotlova^1*, N. M. Ivanova¹, M. P. Yusupova¹, T. L. Voyushina¹, N. E. Ivanushkina², and G. G. Chestukhina¹

¹The Scientific Research Institute for Genetics and Selection of Industrial Microorganisms, 1-yi Dorozhny pr. 1, 113545 Moscow, Russia; fax: (495) 315-0501; E-mail: Kotlova@genetika.ru

²Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Moscow Region, Russia

^* To whom correspondence should be addressed.

Received July 10, 2006; Revision received September 20, 2006

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An extracellular thiol-dependent serine proteinase was isolated from culture medium filtrate of the microscopic fungus Paecilomyces lilacinus with a yield of 33%. The enzyme is inactivated by specific inhibitors of serine proteinases, phenylmethylsulfonyl fluoride, as well as by chloromercuribenzoate and mercury acetate, but is resistant to chelating agents. The proteinase has broad specificity, hydrolyzes proteins and p-nitroanilides of N-acylated tripeptides, exhibiting maximal activity in hydrolysis of substrates containing long hydrophobic and aromatic residues (norleucine, leucine, phenylalanine) as well as arginine at the P1 position. The enzyme has a molecular weight of 33 kD. The enzyme is most active at pH 10.0-11.5; it is thermostable and is characterized by broad optimum temperature range (30-60°C), displaying about 25% of maximal activity at 0°C. The N-terminal sequence of the enzyme (Gly-Ala-Thr-Thr-Gln-Gly-Ala-Thr-Gly/Ile-Xxx-Gly) has no distinct homology with known primary structures of serine proteinases from fungi and bacilli. Based on its physicochemical and enzymatic properties, the serine proteinase from P. lilacinus can be classified as a thiol-dependent subtilisin-like enzyme.

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KEY WORDS: Paecilomyces lilacinus, extracellular serine proteinase, subtilisin, substrate specificity

DOI: 10.1134/S0006297907010142

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