Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amide content of neocarzinostatin (NCS), an antitumor protein, has been determined by analysing asparagine and glutamine in the Pronase-aminopeptidase M digests of tetra-S-carboxymethyl-NCS and carboxyl-modified NCS (modified with a water-soluble carbodiimide and [14C]glycine methyl ester). Preneocarzinostatin (PRE) was separated and purified from a crude NCS preparation by CM-cellulose column chromatography. PRE was found to contain one mole less asparagine than NCS, and asparagine was deamidated to aspartic acid in PRE. A time-dependent conversion of NCS to PRE at pH 3.2 at 4 degrees or in 0.1 M acetic acid at 26 degrees was studied in two ways; first, by quantitative determination of NCS and PRE by CM-cellulose column chromatography and second, by following the release of free NH3 during dialysis in an air-tight container. Within experimental error, PRE was indistinguishable from NCS in amino acid content after acid hydrolysis, as well as in apparent molecular weight as determined by SDS-disc gel electrophoresis (10% acrylamide), and N- and C-terminal amino acid residues. Both NCS and PRE shared a common antigenicity as determined by Ouchterlony's agar diffusion method. Only a slight difference between the two in electrophoresis on a cellulose acetate membrane and on a peptide map of the tryptic digest was demonstrated. PRE, however, was completely devoid of biological activity. In addition to the chromatographic difference, a conformational difference was observed by CD spectroscopy, namely, an apparently looser structure of PRE was indicated by the shallowness of the trough in the 240-265 nm region. This interpretation was supported by the finding that digestions by Pronase were more extensive with PRE than with NCS. These results indicate an important role of the single asparagine residue (Asn 83) of NCS in the biological activity, which is evidently governed by the conformation.
 ...
PMID:Spontaneous deamidation of a protein antibiotic, neocarzinostatin, at weakly acidic pH. Conversion to a homologous inactive preneocarzinostatin due to change of asparagine 83 to aspartic acid 83 accompanied by conformational and biological alterations. 1 34

The subunit composition, the thiol group content and the biological activities of cardiac tropomyosins (TM) of various animal species were compared. Cardiac TM from small animals such as rabbit, guinea-pig, rat and dog contain 2 SH/mole and were resolved into one band on SDS and acid urea electrophoresis and into two bands on alkaline urea electrophoresis. Chicken cardiac TM likewise gave one band and it contains 4 SH/mole. In contrast pig, sheep and human cardiac TM contain respectively 2.6, 2.4, and 2.4 SH/mole and were resolved into two bands alpha and beta on the different electrophoresis systems used, with a beta:alpha ratio respectively of I:4.2, I:4.6, I:4.8. The alpha-TM components from sheep skeletal and pig and sheep cardiac muscles were more positively charged than the rabbit skeletal alpha-TM component, as shown in alkaline urea electrophoresis system. The alphaalpha and alphabeta combinations of dimers found for skeletal muscle by other authors, were also found for cardiac pig TM. All the TM have the same effect on the Ca2+-stimulated ATPase activity of desensitized actomyosin (DAM) and on the Mg2+-stimulated ATPase activity of DAM with troponin-complex. This work suggests that the subunits of the TM from skeletal and cardiac muscles are heterogenous in their M.W. and their charges and that in the heart as well as in skeletal muscle a relationship seems to exist between the amount of the beta component and the speed of contraction of the muscle: a higher amount of this component was found in the bulky hearts which are also those which contract slower.
 ...
PMID:A comparative study of skeletal and cardiac tropomyosins: subunits, thiol group content and biological activities. 13 Dec 98

1. The myosin content of myofibrils was found to be 51% by SDS-gel electrophoresis. 2. The initial burst of Pi liberation of the ATPase [EC 3.6.1.3] of a solution of myofibrils in 1 M KCl was measured in 0.5 M KCl, and found to be 0.93 mole/mole of myosin. 3. The amount of ADP bound to myofibrils during the ATPase reaction and the ATPase activity were measured by coupling the myofibrillar ATPase reaction with sufficient amounts of pyruvate kinase [EC 2.7.1.40] and PEP to regenerate ATP. The maximum amount of ADP bound to myofibrils in 0.05M KCl and in the relaxed state was about 1.5 mole/mole of myosin. On the other hand, the ATPase activity exhibited substrate inhibition, and the amount of ATP required for a constant level of ATPase activity was smaller than that required for the maximum binding of ADP to myofibrils. 4. The maximum amount of ADP bound to myofibrils in 0.5 M KCl was about 1.9 mole/mole of myosin. When about one mole of ADP was found to 1 mole of myosin in myofibrils, the myofibrillar ATPase activity reached the saturated level, and with further increase in the concentration of ATP one more mole of ADP was found per mole of myosin.
 ...
PMID:Structure and function of the two heads of the myosin molecule. I. Binding of adenosine diphosphate to myofibrils during the adenosinetriphosphatase reaction. 13 77

Subfragment-1 of HMM was prepared by tryptic [EC 3.4.21.4] digestion of HMM, which had been modified with 1 mole of CMB per mole of HMM at a specific SH group, SHr. S-1(T) obtained from CMB-HMM retained almost all the CMB, and the amount of bound CMB was about 0.8-0.9 mole per 2 moles of S-1(T). S-2 of CMB-HMM contained no bound CMB. The ATPase [EC 3.6.1.3] activity of HMM increased gradually with increase in the concentration of FA, and the acto-HMM ATPase was inhibited by excess substrate or removal of Ca2+ ions in the presence of RP. The ATPase activity of CMB-HMM increased to a maximum level on adding a small amount of FA, and the acto-CMB-HMM ATPase showed neither substrate inhibition nor Ca2+ sensitivity in the presence of RP. On the other hand, the dependence on the concentration of FA of the ATPase activity of acto-S-1(T) was unaffected by modification of S-1 with CMB. The Ca2+ sensitivity of the ATPase activity of acto-S-1(T) in the presence of RP was also unaffected by the modification. Acto-S-1(T) dissociated almost completely, while acto-CMB-S-1(T) was only 50% dissociated on adding ATP. More than 80% of the bound CMB was contained in S-1(T) undissociated from FA. Furthermore, superprecipitation of actomyosin induced by ATP was completely inhibited by adding about 2 moles of CMB-S-1(T) per mole of actin monomer. On the other hand, about 90% of the burst size of Pi liberation was retained in S-1(T) dissociated from FA. It was concluded that the two heads of the myosin molecule are different: one shows the initial burst of Pi liberation, and does not contain the SHr group which binds CMB (head B), and the other does not show the initial burst and contains the SHr group (head A). It was also concluded that modification of head A of HMM or myosin with CMB increases its binding strength to FA, and consequently the substrate inhibition and Ca2+ sensitivity of acto-HMM or actomyosin ATPase at head B are lost on modification of head A with CMB. CMB-S-1(CT) was prepared by chymotryptic [EC 3.4.21.1] digestion of CMB-myosin, and separated into two fractions by ultracentrifugation of acto-CMB-S-1(CT) in the presence of ATP. Three components of CMB-S-1(CT) with molecular weights of 9, 2.4, and 1.2 X 10(4) were separated by SDS-polyacrylamide gel electrophoresis. The ratios of the peak areas of the three components in electrophoretograms were the same in CMB-S-1(CT) and in the two fractions (1 : 0.18 : 0.09), indicating that heads A and B have the same subunit structure.
 ...
PMID:Structure and function of the two heads of the myosin molecule. III. Cooperativity of the two heads of the myosin molecule, shown by the effect of modification of head A with rho-chloromercuribenzoate on the interaction of head B with F-actin. 13 79

The time course of binding of N-ethylmaleimide (NEM) to the SR was measured at pH 7.5 in the presence or absence of ATP or ADP. The following results were obtained. 1. Both in the presence and absence of nucleotide, the ATPase [EC 3.6.1.3] activity decreased linearly with increase in the amount of NEM bound to the fragmented sarcoplasmic reticulum (SR), and was inhibited almost completely by the binding of 2 moles of NEM per 10(5) g of the SR protein. 2. The amount of NEM incorporated into the ATPase (M.W.=105,000) was measured by SDS disc-gel electrophoresis. It was shown that the ATPase activity was inhibited almost completely by the binding of 2 moles of NEM per mole of ATPase. 3. The rate of binding of NEM to SR decreased by 30-40% in the presence of either ATP or ADP. The concentrations of both ATP and ADP for half-saturation were 0.1-0.2mM. 4. The effect of nucleotide on the rate of binding of NEM was not changed by the presence of Ca2+ and Mg2+ ions. Similar effects were also observed even when the SR membranes were solubilized with Triton X-100. It is suggested from these results that one or two SH groups are located in the active site of the SR ATPase, and that conformational changes are induced by the addition of ATP and ADP.
 ...
PMID:Chemical modification of the Ca2+-dependent ATPase of sarcoplasmic reticulum from skeletal muscle. I. Binding of N-ethylmaleimide to sarcoplasmic reticulum: evidence for sulfhydryl groups in the active site of ATPase and for conformational changes induced by adenosine tri- and diphosphate. 18 70

Biospecific affinity chromatography has been used to purify specific cyclic AMP and cyclic GMP receptor proteins. Several variables are important for successful purification of the cyclic AMP receptor protein, the most critical being the length of the aliphatic spacer side arm. 8-(2-Aminoethyl)-amino-cyclic AMP coupled to the aliphatic spacer side arm. 8-(2-Aminoethyl)-amino-cyclic AMP coupled to agarose specifically retains the cyclic AMP receptor protein by interaction with the immobilized nucleotide. Binding of the cyclic AMP receptor subunit of cyclic AMP-dependent protein kinase to the immobilized nucleotide results in dissociation of the catalytic protein phosphokinase subunit which is not retained. The retained cyclic AMP receptor protein is subsequently eluted by cyclic AMP. Homogeneous cyclic AMP receptor protein prepared from rabbit skeletal muscle by affinity chromatography has been characterized. The molecular weight of the native protein as determined by analytical ultracentrifugation and polyacrylamide gel electrophoresis at varying acrylamide concentrations is 76 800 and 82 000, respectively. The protein is asymmetric with frictional and axial ratios of 1.64 and 12. SDS and urea polyacrylamide gel electrophoresis indicate that the native cyclic AMP receptor is composed of two identical subunits of 42 700 molecular weight. The native protein dimer binds 2 moles of cyclic AMP per mole of protein and is active in suppressing activity of isolated catalytic subunits of cyclic AMP-dependent protein kinase. Cyclic GMP receptor protein from bovine lung has been purified using the same affinity chromatography media. Since cyclic nucleotide binding to cyclic GMP-dependent protein kinase does not result in dissociation of regulatory receptor and catalytic phosphotransferase subunits, the cyclic GMP-dependent protein kinase holoenzyme is retained on the column and can be subsequently specifically eluted with cyclic GMP.
 ...
PMID:The use of affinity chromatography in purification of cyclic nucleotide receptor proteins. 18 11

Ribulose-diphosphate carboxylase from Thiobacillus novellus has been purified to hemogeneity as observed by polyacrylamide gel electrophoresis and U.V. light observation during sedimentation velocity analysis. The optimum pH for the enzyme with Tris-HCl buffers was about 8.2. Concentrations of this buffer in excess of 80 mM were inhibitory. The apparent Km for RuDP was about 14.8 muM with a Hill value of 1.5, for HCO3- the apparent Km was about 11.7 mM with an n value of 1.18 and for Mg2+ about 0.61 mM. The enzyme was specific for this cation. Relatively high concentrations of either Hg2+ or pCMB were required before significant inhibition was observed. Activity declined slowly during a 4-hr incubation period in either 3.0 M or 8.0 M urea. Incubation for 12 hrs resulted in complete loss of activity which was not prevented by 10 mM Mg2+ and was not reversed by dialysis and subsequent addition of 10 mM cysteine. Polyacrylamide gel electrophoresis revealed a loss of the major band and the appearance of 2 new bands. SDS polyacrylamide gel electrophoresis gave an average M.W. of 73500 +/- 2500 for the slower moving band and 12250 +/- 2500 for the faster moving. However, incubation in urea for up to 40 hrs revealed a decrease in the M.W. of the slower moving band to about 60000. The Ea for the enzyme was calculated to be about 18.85 kcal mole-1, with the possibility of a "break" between 40 and 50 degrees C. The Q10 was 3.07 between 20 and 30 degrees C whereas between 30 to 40 degrees C it was 3.31. Only phosphorylated compounds caused significant inhibition of enzyme activity. They included ADP, FDP, F6P, G6P, PEP, 6PG, 2-PGA, R1P, R5P, and Ru5p.
 ...
PMID:Properties and regulation of ribulose diphosphate carboxylase from Thiobacillus novellus. 24 94

Metaphase chromosomes from the Chinese hamster cell line M3-1 were separated by means of a flow sorter. Two chromosome fractions were used for this study: A, which consisted of 95% pure chromosome no. 1, and B, which was 90% pure chromosome no. 2. The DNA of 10(6) chromosomes of each type was purified, and a 125I-cRNA transcript was synthesized in a reaction containing E. coli RNA polymerase and carrier-free 125I-CTP (1.7 Ci/mumole). The cRNA product synthesized with template DNA from 10(5) sorted chromosomes contained more than 10(6) dpm. The electrophoretic mobility profiles of the cRNAs on 7.5% SDS acrylamide gels demonstrated that more than 50% of the ribo-polymers were equal to or longer than marker E. coli met-tRNAf. In hybridization reactions 21% and 17% of the transcripts from Chinese hamster whole cell and sorted chromosome DNA hybridized to Chinese hamster DNA and did not hybridize significantly over background in reactions containing calf DNA at Crt values of 1.3 and 1.9 x 10(2) mole sec/l. Labelled cRNAs transcribed from the DNA of sorted chromosomes hybridized with the DNA of each sorted chromosome fractions at a Crt of 0.6 mole sec/l. This study demonstrated that the DNA can be (1) recovered from small numbers of highly purified flow sorted chromosomes, (2) used as template by E. coli RNA polymerase and (3) used to prepare a cRNA in reactions containing polymerase and carrier-free 125I-CTP to yield a product which can be employed for hybridization analysis.
 ...
PMID:Transcription and hybridization of 125I-cRNA from flow sorted chromosomes. 42 70

Radioactively labeled tubulin from Chinese hamster ovary (CHO) cells can be isolated by co-polymerization with nonradioactive porcine brain microtubule protein. 75% of the soluble tubulin in CHO extracts co-polymerizes with the porcine protein through several cycles, without preferential loss of either CHO or porcine subunits. After phosphocellulose chromatography of the co-polymerized microtubules, the CHO tubulin is radiochemically homogeneous, as judged by SDS-polyacrylamide gel electrophoresis. CHO tubulin purified in this way has 1 mole of nucleotide per mole of protein noncovalently bound at the non-exchangeable or N site. This-layer chromatography indicates that the N site nucleotide is entirely ribo-GTP. Label and chase experiments show that the N site GTP exchanges intracellularly with a half-time of 33 hr in growing cells which have a generation time of 17 hr, while the tubulin polypeptides are degraded with a half-time of 48 hr. Intracellular hydrolysis of the gamma-phosphate of the N site nucleotide can be detected but occurs very slowly, with a half-time of 24 hr. These results suggest that the N site nucleotide may function in vivo as a stable structural co-factor of the tubulin molecule and render improbable the possibility that it has a regulatory role in microtubule assembly.
 ...
PMID:Turnover of tubulin and the N site GTP in Chinese hamster ovary cells. 56 16

Circular DNA was isolated from mitochondrial fractions of ram spermatozoa by SDS treatment followed by convex sucrose gradient centrifugation. The DNA had a contour length of 5.0 micron. Its buoyant density was 1.6983 g cm-3, which was smaller than two nuclear DNA components with buoyant densities of 1.6999 and 1.7156 g cm-3, found in ram spermatozoa. The Tm of the mitochondrial DNA was 69.7 degrees C. The mole fraction G+C calculated from the buoyant density and melting temperature was 39.1% and 38.6%, respectively.
 ...
PMID:Ram sperm mitochondrial DNA. 61 Aug 81


1 2 3 4 5 6 7 8 9 10 Next >>