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PIG BRAIN GLUTAMINASE: PURIFICATION AND IDENTIFICATION OF DIFFERENT ENZYME FORMS
Author(s) -
SVENNEBY G.
Publication year - 1970
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1970.tb03729.x
Subject(s) - glutaminase , tris , amidohydrolase , enzyme , chemistry , substrate (aquarium) , phosphate , chromatography , biochemistry , enzyme assay , glutamine , biology , amino acid , ecology
—Pig brain glutaminase (EC 3.5.1.2 L‐glutamine amidohydrolase) has been purified about 5000‐fold from acetone powder. Glutaminase exists in different molecular forms, dependent on the ionic composition of the buffer. The three main forms are similar to those of kidney glutaminase and therefore called the tris‐HCl enzyme, the phosphate enzyme, and the phosphate‐borate enzyme. The sedimentation coefficients, as estimated by sucrose gradient technique, are 7·3, 8·7, and 53, respectively. Glutaminase has a pH optimum of about 9, but the pH curves of the tris‐HCl enzyme and the phosphate‐borate enzyme have different shapes. The apparent pK 1 of the tris‐HCl enzyme‐substrate complex is similar to pK 2 of inorganic phosphate, the apparent pK 2 of both the tris‐HCl and the phosphateborate enzyme complexes is similar to pK 2 of glutamine. By use of the electron microscope we were able to see the phosphate‐borate enzyme.