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961.
H. Sumi T. Kosugi N. Toki H. Mihara 《Cellular and molecular life sciences : CMLS》1985,41(12):1546-1548
Summary Elastase digested urokinase (ED-UK) was prepared from human high mol. wt urokinase (HMW-UK). It resembled low mol. wt urokinase (LMW-UK) in its mol. wt, specific activity, and active sites. The steady-state kinetic parameters of each enzyme for the activation of human Glu-plasminogen also resembled each other, as did their amidase parameters (with pyro-Glu-Gly-Arg-pNA). 相似文献
962.
Acylphosphatase is one of the smallest enzymes known (about 98 amino acid residues). It is present in organs and tissues
of vertebrate species as two isoenzymes sharing over 55% of sequence homology; these appear highly conserved in differing
species. The two isoenzymes can be involved in a number of physiological processes, though their effective biological function
is not still certain. The solution and crystal structures of different isoenzymes are known, revealing a close packed protein
with a fold similar to that shown by other phosphate-bind ing proteins. The structural data, together with an extended site-directed
mutagenesis investigation, led to the identification of the residues involved in enzyme catalysis. However, it appears unlikely
that these residues are able to perform the full catalytic cycle: a substrate-assisted catalytic mechanism has therefore been
proposed, in which the phosphate moiety of the substrate could act as a nucleophile activating the catalytic water molecule.
Received 12 November 1996; accepted 27 November 1996 相似文献
963.
964.
Early postnatal treatment of rats or mice with different enzyme inducers (cortisol, galactose, steroid which induces mixed function oxidases) results in long-lasting changes in the activity of corresponding inducible enzymes. 相似文献
965.
The male gametogenic development of the immature rat shows inhibitory effect by the exogenous infusion of ACTH (0.25 IU and 0.50 IU; i.p.). Seminiferous tubular degeneration, Leydig cell atrophy and Sertoli cell regression are very conspicuous in the dosage of 0.50 IU ACTH (i.p.). Cytometrical and histological evidence confirms that ACTH could be inhibited by FSH during male gametogenic development which leads to cellular degeneration of testes in the immature rat. 相似文献
966.
967.
Bound gossypol levels in the spleen and kidney of rats ingesting dietary gossypol (0.98%) varied directly with the feeding intervals of 6, 14, 28 and 35 days. Free gossypol level in the kidney, spleen and lungs increased for 14 days and then tended to decrease as the feeding period was extended. 相似文献
968.
969.
L. Barsanti V. Passarelli P. Gualtieri 《Cellular and molecular life sciences : CMLS》1990,46(3):255-256
Summary In vivo microspectroscopy represents an effective and reliable technique to study pigment composition and distribution. In contrast to traditional extractive techniques, it preserves the integrity of biological specimens, without modifying the nature of the pigments. The spectroscopic apparatus we used is very simple and consists of a common microscope equipped with a monochromator, a photomultiplier, and two pinhole diaphragms. Absorption spectra obtained by means of this apparatus on different species of cyanobacteria are presented. 相似文献
970.
Effects of parathyroid hormone and calcitonin on carbonic anhydrase location in osteoclasts of cultured embryonic chick bone 总被引:1,自引:0,他引:1
The ultrastructural location of carbonic anhydrase has been examined in osteoclasts of cultured embryonic chick metatarsi. In untreated cultures and in those to which parathyroid hormone (PTH) was added, the enzyme was found in close association with the plasma membrane of the ruffled border. After brief calcitonin treatment (10 min) the ruffled border disappeared and the association of carbonic anhydrase with the plasma membrane was diminished. The results indicate that the hormones employed act directly on embryonic bone to alter osteoclast structure and the intracellular location of carbonic anhydrase. 相似文献