Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In rat cardiac sarcolemmal membranes a phosphoinositide-specific phospholipase C (PLC) was found to be present. The enzyme hydrolysed exogenous [3H-]phosphatidylinositol 4,5-biphosphate ([3H-]PtdIns(4,5)P2) in an optimized assay mixture containing 15 micrograms SL protein, 100 mM NaCl, 1 mM free Ca2+, 14 mM Na-cholate and 20 microM [3H-]PtdIns-(4,5)P2 (400-500 dpm/microliter) in 30 mM HEPES-Tris buffer (pH 7.0). The average specific activity was 9.14 +/- 0.55 nmol.mg-1.2.5 min-1. The addition of Mg2+ to the assay mixture did not change PLC activity but increased the relative amounts of dephosphorylated inositol products. In the absence of Na+ and at a low Ca2+ concentration (0.3 microM), Mg2+ also enhanced the intraSL levels of PtdIns4P and PtdIns, and, moreover, inhibited PLC activity (IC50-0.07 mM). PtdIns4P seemed to be a good substrate for th rat SL PLC (23.07 +/- 1.57 nmol.mg-1.2.5 min-1) whereas PtdIns was hydrolysed at a very low rate (0.36 +/- 0.08 nmol.mg-1.2.5 min-1). Unlike PtdIns(4,5)P2, PLC-dependent PtdIns4P and PtdIns hydrolysis was not inhibited by Ca2+ concentrations over 1 mM. The possibility of distinct isozymes being responsible for the different hydrolytic activities is discussed.
Mol Cell Biochem 1992 Oct 21
PMID:The substrate specificity of phosphoinositide-phospholipase C in rat heart sarcolemma. 133 20

Aspartate-beta-semialdehyde dehydrogenase catalyzes the NADPH-mediated reductive dephosphorylation of beta-aspartylphosphate at a branch point in the biosynthesis of several amino acids. The enzyme from Escherichia coli has been crystallized by the vapor diffusion method from Tris buffer (pH 8.5) using polyethylene glycol 4000 as a precipitant. The crystals are orthorhombic and have the symmetry of space group P222(1), with unit cell dimensions of a = 177.8 A, b = 59.9 A, c = 118.65 A, and alpha = beta = gamma = 90 degrees. The dimensions and space group are indicative of two enzyme dimers (40 kDa per subunit) in the asymmetric unit. The crystals show strong diffraction, and a native data set has been collected to 2.5 A resolution.
J Mol Biol 1992 Nov 05
PMID:Crystallization and preliminary crystallographic analysis of aspartate-beta-semialdehyde dehydrogenase from Escherichia coli. 136 28

We have shown that the second intron of the Podospora mitochondrial gene coding for cytochrome b (Cytb 12) splices autocatalytically, using in vitro transcripts generated from the T7 promoter. The reaction takes place at 37 degrees C in the presence of 50 mM TRIS-HCl pH 7.5, 60 mM MgCl2 and 1 mM GTP but shows a low efficiency even at high KCl concentrations of up to 1.2 M. Under these conditions, intron bI2 follows the conventional pathway of group I splicing, and all characteristic products, with regard to both transesterification and hydrolysis, could be identified. Moreover, the intron is capable of undergoing cyclization, thereby releasing the noncoded G and one additional nucleotide (U) from the 5' end. The 5' cleavage site is preceded by the same two nucleotides, indicating a base-pairing at the same site of the internal guide sequence (IGS) for both splicing and cyclization ("one-binding-site model"). In addition, products resulting from site-specific hydrolysis 138 nucleotides downstream of the 5' splice site were detected. Unusually, the shortened intron is also able to form a circular RNA and an alternative sequence that aligns the cyclization site to the catalytic core of the intron must be assumed.
Mol Gen Genet 1992 May
PMID:Self-splicing of a mitochondrial group I intron from the cytochrome b gene of the ascomycete Podospora anserina. 137 8

A sperm motility inhibitor from boar seminal plasma was purified. The purification procedure included dialysis against 0.1 M Tris-HCl containing 0.1 mM DTT and chromatographies on SP-Sephadex C-25 and Phenyl-Sepharose CL-4B. With this procedure, the seminal plasma motility inhibitor (SPMI) preparation was highly purified with a 18% recovery of inhibitory activity. The molecular weight of SPMI in native conditions has been estimated at 50,000 by molecular sieving, but 3 polypeptides with molecular weights of 14,000, 16,000 and 18,000 were observed following polyacrylamide gel electrophoresis in denaturing conditions. SPMI is a thermolabile basic protein that is stable between pH 6 and pH 11. The observations that SPMI effects on motility of demembranated spermatozoa are reversed by Mg.ATP and that SPMI inhibited bull dynein ATPase in a concentration-dependent manner suggest that this protein blocks the motility of demembranated spermatozoa by interfering with dynein arm function.
Mol Reprod Dev 1992 Jan
PMID:Purification and characterization of a sperm motility-dynein ATPase inhibitor from boar seminal plasma. 153 94

Lipase from Pseudomonas glumae has been purified and crystallized in two forms, using the hanging drop method of vapour diffusion at 4 degrees C and 15 degrees C. Both forms grew at pH 9.0 from 0.1 M-Tris buffer in the presence of 10% (v/v) acetone. Form 1 was crystallized from 27 to 29% polyethylene glycol in the presence of less than 0.5% (v/v) n-dodecyl-beta-D-glucopyranoside. Form 2 was grown from 17 to 19% ammonium sulphate in the presence of 1% n-octyl-beta-D-glucopyranoside. Form 1 is orthorhombic with space group P2(1)2(1)2(1), and cell dimensions of a = 158.1 A, b = 158.6 A, c = 63.4 A, Form 2 is tetragonal with space group P4(1)2(1)2 (or P4(3)2(1)2) and cell dimensions of a = 89.3 A, c = 180.4 A. Form 1 probably has four molecules per asymmetric unit and diffracts to at least 2.5 A. Form 2 has two molecules per asymmetric unit and diffracts to at least 3.0 A.
J Mol Biol 1992 Mar 05
PMID:Crystallization and preliminary X-ray study of a lipase from Pseudomonas glumae. 154 8

In 5 placental homogenates the Km of steroid sulfatase for DHEA sulfate increased from 15.4 in Tris buffer to 26.8 microM in phosphate (both buffers 0.1 M, pH 7.4), P less than 0.05. In 3 pooled ovarian preparations the Km increased from 14.3 microM in Tris to 33.0 microM in phosphate, P less than 0.01. There was no significant difference between the ovarian and placental values for Km in either Tris or phosphate (P greater than 0.5), and the increase in the Km produced by phosphate in ovarian tissue was not significantly different from that in the placenta (P greater than 0.5). In the placentas the Vmax in Tris was 1420 pmol/min/mg protein and this fell to 523 pmol/min/mg protein in phosphate (P less than 0.005). The Vmax was 50-fold higher in the placenta than in the ovary in either Tris or phosphate (both P less than 0.001). In the ovary, the Vmax was 27.6 pmol/min/mg protein in Tris and 11.0 pmol/min/mg protein in phosphate (P less than 0.05). The reduction of Vmax produced by phosphate in the ovary was not significantly different from that in the placenta (P greater than 0.5). The slope of the 1/v vs 1/S plot (Km/Vmax) increased 4.7-fold in the placentas and 5.8-fold in the ovaries in phosphate over that in Tris (both P less than 0.001); the increase in the placentas was not significantly different from that in the ovaries (P greater than 0.5). Phosphate ion acts as a mixed inhibitor of both placental and ovarian steroid sulfatase.
J Steroid Biochem Mol Biol 1992 Feb
PMID:Steroid sulfatase in the human ovary and placenta: enzyme kinetics and phosphate inhibition. 157 Oct 52

[3H]Propionyl-Tyr-(SO3H)-gNle-mGly-Trp-(NMe)Nle-Asp-Phe-NH2 ([3H]pBC 264) (98-100 Ci/mmol), a new peptidase-resistant cholecystokinin (CCK) agonist that is 1000-fold more potent for CCK-B than for CCK-A receptors, interacts, with a similar subnanomolar affinity, with a single class of binding sites (Kd, 0.15-0.2 nM) in brain membranes of mouse, rat, guinea pig, and cat, in Tris and Krebs buffers. The concentration of CCK-A receptors in rodent brain was estimated to be 8-10 fmol/mg of protein, by measurement of the Bmax values of the nonselective agonist [3H] propionyl-CCK8, with or without 10 nM pBC 264 to saturate CCK-B sites. In guinea pig and mouse brain, specific [3H]pBC 264 binding was not affected by NaCl and/or guanyl-5'-yl-imidodiphosphate. In contrast, in rat brain the affinity of [3H]pBC 264 was decreased and the maximal number of binding sites was increased by NaCl and the guanyl nucleotide or by alkaline treatment, suggesting that a proportion of CCK-B receptors are linked to guanine nucleotide-binding proteins. The Bmax of a CCK8 analog, [3H]SNF 8702, was higher (57 fmol/mg of protein) than that of [3H]pBC 264 (40 fmol/mg of protein) in guinea pig brain cortex but not in mouse brain. The relative potencies of various analogs differed among species. The CCK-B antagonist L365,260 was 18-, 30-, and 64-fold less potent than [3H]pBC 264 in guinea pig, mouse, and rat, respectively. PD 134308, a CCK-B antagonist, was 20-fold less potent in rat brain than in guinea pig brain. Likewise, the cyclic analog BC 254 displayed a 30- and 60-fold lower affinity for mouse and rat than for guinea pig brain preparations. Together, these results suggest the presence of CCK-B receptor subtypes. In all tissues, the specific binding of [3H]pBC 264 at its Kd values was very high (75-90%) and higher than that of the hydrophobic CCK-B probe [3H]SNF 8702 (approximately 50%). Therefore, unlike [3H]SNF 8702, [3H]pBC 264 can be used to study preparations with low receptor concentrations, such as rat brain, making this radiolabeled molecule the most appropriate ligand available to date for CCK-B receptor studies.
Mol Pharmacol 1992 Jun
PMID:[3H]pBC 264, a suitable probe for studying cholecystokinin-B receptors: binding characteristics in rodent brains and comparison with [3H]SNF 8702. 161 11

An enzyme able to cleave dinucleoside triphosphates has been purified 3,750-fold from Saccharomyces cerevisiae. Contrary to the enzymes previously shown to catabolize Ap4A in yeast, this enzyme is a hydrolase rather than a phosphorylase. The dinucleoside triphosphatase molecular ratio estimated by gel filtration is 55,000. Dinucleoside triphosphatase activity is strongly stimulated by the presence of divalent cations. Mn2+ displays the strongest stimulating effect, followed by Mg2+, Co2+, Cd2+, and Ca2+. The Km value for Ap3A is 5.4 microM (50 mM Tris-HCl [pH 7.8], 5 mM MgCl2, and 0.1 mM EDTA; 37 degrees C). Dinucleoside polyphosphates are substrates of this enzyme, provided that they contain more than two phosphates and that at least one of the two bases is a purine (Ap3A, Ap3G, Ap3C, Gp3G, Gp3C, m7Gp3A, m7Gp3G, Ap4A, Ap4G, Ap4C, Ap4U, Gp4G, and Ap5A are substrates; AMP, ADP, ATP, Ap2A, and Cp4U are not). Among the products, a nucleoside monophosphate is always formed. The specificity of cleavage of methylated dinucleoside triphosphates and the molecular weight of dinucleoside triphosphatase indicate that this enzyme is different from the mRNA decapping enzyme previously characterized (A. Stevens, Mol. Cell. Biol. 8:2005-2010, 1988).
 ...
PMID:Isolation and characterization of a dinucleoside triphosphatase from Saccharomyces cerevisiae. 165 9

C1r and C1s, the serine protease components of activated C1, form a tetramer in the presence of Ca2+. The stability of this tetramer is sufficient that its association with the third component, C1q, has been successfully treated as a reversible bimolecular equilibrium reaction [Siegel and Schumaker, Molec. Immun. 20, 53-66 (1983)]. We have used the fluorescence anisotropy (A) of fluorescein-labeled C1s (s*) to monitor assembly and subcomponent exchange in 0.15 mol/l NaCl, 0.001 mol/l Ca2+ 0.02 mol/l Tris, pH 7.4. Addition of q to r2s*2 causes a small but measurable delta A of 0.01-0.02. The response is too fast to measure at 37 degrees but can be readily followed at 4 degrees where t 1/2 = 0.6 min when [q] = [r2s*2] = 0.5 mumol/l. The increase in A can be readily reversed by dilution or by addition of unlabeled C1s. Slow incremental addition of q to a solution of r2s*2 produces a dose-dependent delta A from which stoichiometry and dissociation constants can be derived. Measurements of Kd as a function of temperature establish an inverse temperature dependence with delta H = -15 kcal/mol and a value of Kd = 0.031 mumol/l at 37 degrees (delta G = + 11, T delta S = -26 kcal/mol). Thus, the assembly process appears to be entropy-driven presumably due to the exclusion of structured water from protein-protein interfaces in the complex.
Mol Immunol 1992 Jan
PMID:Dynamic equilibria between subcomponents of C1, the first component of human complement. 173 Nov 91

The Ca2+/Mg2+ ATPase, which is activated by millimolar concentrations of Ca2+ or Mg2+, was solubilized from rat heart plasma membrane by employing lysophosphatidylcholine, CHAPS, NaI, EDTA and Tris-HCl at pH 7.4. The enzyme was purified by sucrose density gradient, Affi-Gel Blue column and Sepharose 6B column chromatography. The purified enzyme was seen as a single peptide band in the sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular weight of about 90,000. The apparent molecular weight of the holoenzyme as determined under non-dissociating conditions by gel filtration on Sepharose 6B column was about 180,000 indicating two subunits. The enzyme was insensitive to ouabain, verapamil, vanadate, oligomycin, N,N-dicyclohexylcarbodiimide and NaN3, but was markedly inhibited by 20 microM gramicidin S and 50 microM trifluoperazine. Analysis of the purified Ca2+/Mg2+ ATPase revealed the presence of 17 amino acids where leucine, glutamic acid and aspartic acid were the major components and histidine, cysteine and methionine were the minor components. The purified enzyme was associated with 19.7 mumol phospholipid/mg protein which was 60 times higher than the phospholipid content in plasma membrane. The cholesterol content in the purified enzyme preparation was 0.75 mumol/mg protein and this represented an 8-fold enrichment over plasma membrane. The glycoprotein nature of the enzyme was evident from the positive periodic acid-Schiff staining of the purified Ca2+/Mg2+ ATPase in the sodium dodecyl sulfate polyacrylamide gel. The polysaccharide content of the enzyme was enriched 8-fold over plasma membrane; neuraminidase treatment decreased the polysaccharide content. Concanavalin A prevented the ATP-dependent inactivation of the purified Ca2+/Mg2+ ATPase and was found to bind to the purified enzyme with a KD of 576 nM and Bmax of 4.52 nmol/mg protein. The results indicate that Ca2+/Mg2+ ATPase is a glycoprotein and contains a large amount of lipids.
Mol Cell Biochem 1991 Oct 16
PMID:Purification and composition of Ca2+/Mg2+ ATPase from rat heart plasma membrane. 183 89


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