Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tubulin can stimulate specifically the aryl phosphatase activity of the low-Mr polycation-stimulated (PCSL) phosphatase, measured as p-nitrophenyl phosphatase activity, or using reduced carboxamidomethylated and maleylated (RCM) lysozyme, phosphorylated on tyrosyl residues, as a substrate. This stimulation is independent of the degree of polymerization of tubulin (A50 = 60 nM) and is due to an increase in Vmax. It is mechanistically different from the ATP-induced activation and resistant to heat and trypsin treatment. Chymotrypsin destroys the stimulatory effect of tubulin. The polycation-stimulated phosphorylase phosphatase activity is inhibited by tubulin, probably by a polycation/polyanion interaction. The microtubule-associated protein, MAP2, is inhibitory to the p-nitrophenyl phosphatase activity and tubulin can eliminate this inhibitory effect. MAP2 also inhibits the polycation-stimulated phosphorylase phosphatase activity.
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PMID:Tubulin and MAP2 regulate the PCSL phosphatase activity. A possible new role for microtubular proteins. 254 1

Fractionation of rabbit heterophil leukocyte homogenates by isopycnic centrifugation as well as by zonal sedimentation has helped to characterize further the particulate components of these cells. Four classes have been identified: (A) Large (0.5-0.8 microm) and dense (1.26) azurophil or primary granules, containing all the myeloperoxidase, one-third of the lysozyme, and a major proportion of the lysosomal acid hydrolase activities of the cells. (B) Smaller (0.25-0.40 microm) and less dense (1.23) specific or secondary granules, containing 90% of the alkaline phosphatase and the remainder of the lysozyme activities, but very little if any acid hydrolases. (C) Particles of low density (1.20), containing the remainder of the lysosomal acid hydrolases. This fraction was heterogeneous, but showed abundant small rod- or dumbbell-shaped particles of moderate electron opacity, surrounded by a single membrane (tertiary granules?). The possible origin of these lysosomes from contaminating macrophages could not be ruled out but appeared unlikely. (D) Slowly sedimenting material of very low density (1.14), made up of large, empty vesicular membrane structures, and containing 10% of the alkaline phosphatase, and all of a thiol-dependent acid p-nitrophenyl phosphatase, an enzyme clearly different from the lysosomal acid phosphatase.
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PMID:Further biochemical and morphological studies of granule fractions from rabbit heterophil leukocytes. 545 43