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

The digestion of EF-Tu-GDP (or EF-Tu-GTP) by trypsin [EC 3.4.21.4] under native conditions has been shown to proceed through two different and characteristic stages. 1. In the first phase, the protein is transformed into a fragment (Fragment A) with a molecular weight of 39,000 by exposure to trypsin for a relatively short period of time. Fragment A is unable to catalyze the binding of aminoacyl-tRNA to ribosomes. The ability to promote two partial steps of the binding reaction, i.e., formation of the aminoacyl-tRNA-EF-Tu-GTP ternary complex as well as the methanol-stimulated, ribosome dependent GTPase reaction, was rapidly destroyed. On the other hand, the ability to interact with guanine nucleotides as well as EF-Ts survived well during prolonged digestion. 2. In the second phase of digestion, a nick is introduced in Fragment A to yield two subfragments (Fragments B and C). These two fragments exist as a hybrid molecule which migrates as a single peak on a Sephadex G-75 column, and which dissociates into Fragments B and C only in the presence of 6 M guanidine hydrochloride or 5% sodium dodecyl sulfate. The molecular weights of Fragments B and C, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, were 22,000 and 12,000 respectively. The hybrid molecule still retained one mole of bound guanine nucleotide and was resistant to further tryptic digestion. 3. Three sulfhydryl groups of EF-Tu were found to be present in Fragment B, both by amino acid analysis of the purified fragments and also by electrophoresis of tryptic digests labeled with N-ethyl[14C]maleimide. 4. The tryptic digestion of EF-Tu-GDP (or EF-Tu-GTP) labeled with N-(1-anilinonaphthyl-4)maleimide (ANM) at SH2 (the second SH), caused a 30% decrease in the fluorescence emission during the first rapid phase of digestion. This indicates that destruction of the hydrophobic environment near SH2 of EF-Tu occurred in the early phase of tryptic digestion. 5. The kinetic studies on the reaction of ANM with EF-Tu before and after tryptic digestion indicated that both Fragment A and the hybrid molecule reacted with ANM in the presence of GTP three to four times more rapidly than in the presence of GDP. Thus, it appears that the ability to induce conformational transition near SH2 by a change of nucleotide ligands is still retained in the hybrid molecule consisting of Fragments B and C.
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PMID:Limited hydrolysis of the polypeptide chain elongation factor Tu by trypsin. Isolation and characterization of the polypeptide fragments. 93 63

A radioimmunoassay (RIA) technique has been devised for the measurement of human fibrinopeptide A (FPA). The system utilizes rabbit antiserum to native human FPA and a synthetic fibrinopeptide, with tyrosine substituted for phenylanine in amino acid position 8. The test detects native human FPA at a concentration of 0.1 ng/ml, but does not cross react with human fibrinopeptide B or with fibrinopeptides A from canine, porcine, or bovine fibrinogen. Fibrinogen and chemical or plasmic degradation products with 2 moled of FPA per mole react fully in this test system. This includes the large-molecular-weight intermediate fragments X and Y and the NH2-terminal disulfide knot, and indicates that this antibody recognizes and reacts with FPA in the presence of the contiguous peptide structures present in fibrinogen. Fragment E, which is derived from the NH-2-terminal portion of fibrinogen, loses most of its FPA content after its liberation from its precursor derivative and reacts to a lesser extent in the RIA than do fragments X and Y. This correlated with the recovery of FPA-positive material from ultrafilitrates of extensive but not partial plasmic digests of fibrinogen. Although FPA immunoreactivity liberated from fibrinogen does not necessarily reflect thrombin activity and/or fibrin formation, only extensive plasmic degradation yields peptide material which reacts in this RIA system. This should not be a serious limitation to the application of the RIA in the detection of venous thrombosis.
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PMID:Reaction of plasmic degradation products of fibrinogen in the radioimmunoassay of human fibrinopeptide A. 116 12

The delta RM0(-CH2-) values have been calculated from fragment values of various alkyl groups (methyl, ethyl, n-propyl). On the basis of delta RM0(-CH2-) values it has been established that the value of the so-called "second" methyl group from aromatic ring has slightly differed from that of the so-called third methylene group and the value of methylene functional group is constant independently from positions of substituents and from electronic interactions. The delta RM0 Me values of methyl group--which is directly attached to aromatic ring--have been regarded as the so-called first methylene group from aromatic ring since value of free energy needed for transfer of methyl group as well as the other physico-chemical data (mole volume, parachor) are nearly the same as those of methylene group according to the literature. Fragment values of methyl groups substituted at various positions have been compared to relating delta RM0(-CH2-) value which is free practically from electronic interactions and it has been ascertained that fragment values have been higher as well as lower. In accordance with literature lower delta RM0 Me values have been interpreted with hyperconjugation effect of aromatic system. On the other hand lower methylene fragment values of alkyl substituted compounds at N1 atom have been attributed to sigma conjugation. In literature higher delta RM0 Me values than relating delta RM0(-CH2-) value are known only in case of orto position to another functional group or by a methyl group on a sterically hindered aromatic ring. Results of tests have shown that values of delta RM0 Me can substantially increase with extension of conjugated aromatic system or with simultaneous substitutions of methyl, methylene groups, respectively at certain locations. The authors have assigned that increase to change of solvate cuver which surrounds the molecule. The same has been manifested by methyl fragment values of quinazoline derivates (tetrahydropyrroloquinazoline, hexahydroazepinoquinazoline) of different electronic distributions. On basis of calculations it has been proved that delta RM0 2-Me and delta RM0 6-Me fragment values of monosubstituted pyrido (1,2-a)-pyrimidine (PP) derivatives have significantly differed from delta RM0 Me values of at other positions (3,7,8,9) methyl substituted compounds. Among disubstituted derivatives only delta RM0 7-Me and delta RM0 8-Me values of 2-phenyl- and 3-carbetoxymethyl-PP derivatives have not differed from each other but methyl fragment values of other positions (6,9) have significantly differed from each other and from other fragment values too.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Hydrophobic constant values (delta RMO) of functional groups. II. Interpretation of fragment interactions]. 232 57

Fragment X components (Mr 225,000 to 333,000) were distinguished on sodium dodecyl sulfate polyacrylamide gels. Western blotting with monoclonal antibodies to A alpha-chain segments demonstrated that the A alpha-chains of fibrinogen and the largest fragment X components (Mr 285,000-340,000) contained both A alpha 259-276 and A alpha 540-554. Fragment X components of Mr 270,000-285,000 contained A alpha 259-276 but lacked A alpha 540-554, whereas the smallest fragment X components (Mr 225,000-270,000) contained neither A alpha 540-554 nor A alpha 259-276. Studies of the small peptides generated during fragment X formation complemented the studies of the large molecules, by demonstrating peptides containing both A alpha 259-276 and A alpha 540-554 (Mr 41,600-41,800 and Mr 38,700-38,900), peptides containing A alpha 540-554 but not A alpha 259-276 (Mr 20,500-21,000 and Mr 17,300-17,500) and peptides containing only A alpha 259-276 (Mr 23,600-24,000 and Mr 20,500-21,000). Cleavage of B beta 1-42 from the amino terminal ends of the B beta-chains, measured with a specific radioimmunoassay, was linear until 1.6 moles per mole of fibrinogen had been released, and coincided with loss of the central and carboxy terminal A alpha-chain regions, i. e. A alpha 259-276 and A alpha 540-554. Based on present and previously reported data, a model is proposed for the evolution of the heterogeneous group of fragment X derivatives from fibrinogen with the simultaneous release of small peptides.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Immunologic identification of the cleavage products from the A alpha- and B beta-chains in the early stages of plasmin digestion of fibrinogen. 294 92

Restriction fragment length polymorphism (RFLPs) of the mouse period-homologous sequence were studied in 13 populations of the four chromosomal species (2n = 52, 54, 58 and 60) of the mole rat, Spalax ehrenbergi superspecies in Israel. The period locus of Drosophila melanogaster is implicated in controlling the circadian rhythm as well as the male courtship song rhythm. Multiple DNA homologies exist in the mole rat and correspond to more than 10 loci. The level of polymorphism is very high, with a large number of alleles per locus, increasing from the northern to the southern species along a gradient of increasing aridity. Variation was also found in an isolated desert population, with a unique fragment specific to this population. Fragment variation allows distinction between chromosomal species, and confirms earlier evidence that gene flow does not occur between them. A correlation was found between some allelic fragments and the number of apparent harmonics of the courtship calls. This finding suggests an interesting testable hypothesis that the existence of a locus (homology) is responsible for the courtship call parameters.
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PMID:Period-homologous sequence polymorphisms in subterranean mammals of the Spalax ehrenbergi superspecies in Israel. 809 31

Stretches of residual structure in the unfolded states of proteins could possibly constitute crucial regions that initiate protein folding. We are searching for such regions in barnase by dividing it into fragments. By this means, we can search for regions that just form within local sequences. We are also employing methods that can detect low levels of residual structure. In this study, we examine the fragment 1-22 and a large fragment (23-110) that contains all of the catalytic residues. Fragment 1-22 contains the first alpha-helix, and fragment 23-110 contains the second alpha-helix and beta-sheet structure-forming residues of native barnase. These fragments bind together rapidly and tightly upon association to form a fully native-like complex. Studies by circular dichroism and fluorescence spectroscopy indicate that each fragment is mainly disordered. However, we find by a procedure of titration with trifluoroethanol that about 3% of fragment 1-22 is helical in water at 25 degrees C. Importantly, we have detected residual catalytic activity in fragment 23-110 toward GpUp and RNA and the ability to bind the polypeptide inhibitor of barnase, barstar, suggesting that this fragment can form a native-like conformation in water. The catalytic activity does not result from a small amount of contaminating impurity of parent enzyme or other ribonuclease, since the activity requires a 1:1 mole ratio of fragment to barstar for complete inhibition, and the activity is lost in much lower concentrations of urea than are required to denature the parent enzyme. There is a very weak signal in the near-UV CD spectrum of the large fragment.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Folding of barnase in parts. 814 79