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LIPOPHILIZATION OF MUCOR MIEHEI ASPARTYL PROTEINASE: EFFECT ON STRUCTURE‐FUNCTION AND STABILITY
Author(s) -
SMITH J. L.,
YADA R.Y.
Publication year - 1991
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1991.tb00419.x
Subject(s) - chemistry , circular dichroism , myristoylation , enzyme , protein tertiary structure , thermal stability , dtnb , biochemistry , proteinase k , glutathione , organic chemistry , phosphorylation
The effect of lipophilization on the structure‐function and stability of Mucor miehei aspartyl proteinase (MMP) was examined. Modification of approximately 3 and 2 e‐amino groups in MMP with caproyl and myristoyl chloride, respectively, decreased the proteolytic activity (PA) and milk‐clotting activity (MC) of the enzyme; differential reduction in these activities was manifest as increased MC/PA. Lipophilized MMP also showed significantly higher thermal, kinetic and conformational stability. Interaction between fatty acids and proteinase appeared to be ionic in nature, as evidenced by increased relative electrophoretic (cathodic) mobility. Attachment of the fatty acid ligands was shown to increase both aliphatic and aromatic hydrophobicity of MMP as indicated by the hydrophobic fluorescent probes cis‐parinaric acid and l‐anilino‐8‐naphthalenesulfonate. Lipo‐philization‐induced changes in functional properties were accompanied by altered secondary and tertiary structure as reflected by far‐UV and near‐ UV circular dichroism spectra, respectively. Results of this study suggesed that high MC/PA may be related to high hydrophobicity in aspartyl proteinases.