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Biomedical subjects

J H Collins

Publications and source records attributed to J H Collins.

At least 145 records · Page 8Linked to original sources
PubMed1979

Large-scale purification of Na,K-ATPase and its protein subunits from lamb kidney medulla.

Procedures are described for the large-scale isolation of purified Na,K-ATPase (EC 3.6.1.3) from frozen lamb kidney outer medulla and for the separation of its two protein subunits by hydroxyapatite chromatography in sodium dodecyl sulfate (SDS). The methods described permit the routine isolation of up to 800 mg of purified Na,K-ATPase in one week, which can subsequently be separated into 500 mg of mr = 95,000 catalytic subunit and 200 mg of glycoprotein with four SDS-hydroxyapatite column runs.

Animals↗
PubMed1978

The isolated heavy chain of an Acanthamoeba myosin contains full enzymatic activity.

Acanthamoeba myosin IB is a single-headed enzyme containing one heavy chain of 125,000 daltons, one light chain of 27,000 daltons, and one light chain of 14,000 daltons. The 125,000- and 27,000-dalton polypeptides are consistently found in a molar ratio of 1:1. The content of the 14,000-dalton peptide is usually only 0.1 to 0.2, and always less than 0.5, relative to the other two chains and might be a contaminant or a degradation product of one of the other chains. The specific activities of the Ca2+-ATPase, (K+, EDTA)-ATPase, and (after phosphorylation of its heavy chain by a specific kinase) actin-activated Mg2+-ATPase of Acanthamoeba myosin IB are similar to those of rabbit skeletal muscle myosin. After treatment of the enzyme with 2 M LiCl, the 125,000-dalton heavy chain of Acanthamoeba myosin Ib can be obtained, by chromatography on Sephadex G-200, essentially free of the 14,000-dalton peptide and more than 90% free of the 27,000-dalton peptide. This isolated heavy chain has the same specific ATPase activities as the original enzyme. Therefore, the heavy chain of Acanthamoeba myosin IB contains the ATPase catalytic site, the actin-binding site, and the phosphorylation site and is fully active enzymatically in the absence of light chains.

Adenosine Triphosphatases↗
PubMed1977

Determination of the amino acid sequence of troponon C from rabbit skeletal muscle.

The complete amino acid sequence of rabbit skeletal muscle troponin C (TnC) was determined from studies on overlapping peptides isolated from cyanogen bromide and tryptic digests. TnC was found to be a single polypeptide chain of 159 amino acid residues, including 2 residues of tyrosine and 1 each of cysteine, histidine, and proline. The amino end is acetylated, the calculated net charge at pH 7.0 is -29, and the calculated molecular weight is 17,965. There was no evidence for heterogeneity in the sequence. The previously proposed four apparent Ca2+ binding sites are located at residues 27 to 38, 63 to 74, 103 to 114, and 139 to 150.

Amino Acid Sequence↗
PubMed1977

Acyl group and electron pair relay system: a network of interacting lipoyl moieties in the pyruvate and alpha-ketoglutarate dehydrogenase complexes from Escherichia coli.

The dihydrolipoyl transacetylase component of the Escherichia coli pyruvate dehydrogenase complex [pyruvate:lipoate oxidoreductase (decarboxylating and acceptor-acetylating), EC 1.2.4.1] bears two sites on each of its 24 polypeptide chains that undergo reductive acetylation by [2-(14)C]pyruvate and thiamin pyrophosphate, acetylation by [1-(14)C]acetyl-CoA in the presence of DPNH, and reaction with N-ethyl[2,3-(14)C]maleimide in the presence of pyruvate and thiamin pyrophosphate. The data strongly imply that these sites are covalently bound lipoyl moieties. The results of similar experiments with the E. coli alpha-ketoglutarate dehydrogenase complex [2-oxoglutarate:lipoate oxidoreductase (decarboxylating and acceptor-succinylating), EC 1.2.4.2] indicate that its dihydrolipoyl transsuccinylase component bears only one lipoyl moiety on each of its 24 chains. Charging of the 48 acetyl acceptor sites on the transacetylase or the 24 succinyl acceptor sites on the transsuccinylase by pyruvate or alpha-ketoglutarate, respectively, and thiamin pyrophosphate was observed in the presence of only a few functionally active pyruvate dehydrogenase or alpha-ketoglutarate dehydrogenase chains. Extensive crosslinking of the transacetylase chains was observed when the pyruvate dehydrogenase complex was treated with pyruvate and thiamin pyrophosphate or with DPNH in the presence of N,N'-o- or N,N'-p-phenylenedimaleimide, respectively. When the alpha-ketoglutarate dehydrogenase complex was treated with DPNH in the presence of N,N'-p-phenylenedimaleimide, only transsuccinylase monomers and crosslinked transsuccinylase dimers were detected. It appears that the 48 lipoyl moieties in the transacetylase and the 24 lipoyl moieties in the transsuccinylase comprise an interacting network that functions as an acyl group and electron pair relay system through thiol-disulfide and acyl-transfer reactions among all of the lipoyl moieties.

Acetyl Coenzyme A↗
PubMed1977

Amino acid sequence of a myosin fragment that contains SH-1, SH-2, and Ntau-methylhistidine.

A peptide having 92 amino acid residues and a calculated molecular weight of 10,478 was isolated from a cyanogen bromide digest of rabbit skeletal muscle myosin. It contained both proline and Ntau-methylhistidine, indicating that it arose from the portion of the heavy chain that folds to form most of the globular head of the myosin molecule. The amino acid sequence of the peptide included the two sulfhydryl groups whose alkylation modifies myosin's catalytic properties: SH-2 at position 11 in the peptide, and SH-1 at position 21. This proximity in the sequence means that SH-1 and SH-2 must be relatively close together in myosin, and several lines of evidence suggest that this region is near the catalytic or actin binding site(s) of myosin.

Adenosine Triphosphate↗
PubMed1976

Current status of the treatment of epidermoid cancer of the vulva.

Epidermoid cancer accounts for 81% of the malignancies of the vulva. Although the etiology has not been delineated, chronic vulvitis is associated with cancer in almost one-third of the patients. The staging system should utilize the most precise and accurate parameters delineated for improved treatment. A new staging system is utilized. Proven treatment is primarily surgical.

Carcinoma, Squamous Cell↗
PubMed1976

Carcinoma in situ of the cervix uteri in pregnancy.

After reviewing the charts of patients at the Tulane Unit of Obstetrics and Gynecology of Charity Hospital between the years 1950 and 1970, 25 patients were noted to have carcinoma in situ of the cervix uteri associated with pregnancy. Twenty-two patients had positive Papanicolaou smears. Subsequently, 20 patients had conization of the cervix uteri to exclude an invasive lesion. Vaginal delivery was accomplished in 17 of the patients. After complete re-evaluation, definite treatment was done six to eight weeks post partum, and there were no recurrences or deaths from the disease.

Adult↗
PubMed1975

The primary structure of actin from rabbit skeletal muscle. Five cyanogen bromide peptides, including the NH2 and COOH termini.

As a part of a study of the complete amino acid sequence of actin we have determined the sequences of five cyanogen bromide peptides, which together contain 158 amino acid residues, including the two ends of the molecule. The five peptides are: CB-13 (residues 1 to 44 in the intact chain), CB-11 (residues 83 to 119), CB-12 (residues 228 to 268), CB-8 (residues 283 to 298), and CB-9 (residues 355 to 374). Each of the peptides except CB-11 has one sulfhydryl group, and these peptides thus account for 4 of the 5 cysteines in actin. The reactivity of actin --SH groups toward N-ethylmaleimide was investigated, and it was found that Cys-373 (in CB-9 adjacent to the COOH-terminal phenylalanine) is the first to react with this reagent.

Actins↗
PubMed1975

The primary structure of actin from rabbit skeletal muscle. Completion and analysis of the amino acid sequence.

Actin is the principal constituent of the thin filaments of muscle, and in order to provide information basic to understanding the molecular basis of actin function we have studied its amino acid sequence. The isolation, compositions, and sequences of cyanogen bromide peptides, ranging in size from 3 to 44 residues, have previously been reported (ELZINGA, M. (1971) Biochemistry 10, 224-229, and other papers in the present series). The peptides have been aligned by isolation and characterization of tryptic peptides that contain methionine. The isolation of one of the CNBr peptides (CB-14) was complicated by the presence of a Met-Thr bond that was only partially split under standard conditions for cyanogen bromide cleavage in formic acid. In this paper conditions are described for increasing the cleavage at this bond. CB-14 is a tetrapeptide, Thr-Gln-Ile-Hse, and this sequence completes the characterization of the actin cyanogen bromide peptides. Finally, the position of CB-14 in the actin sequence as residues 120 to 123 was established by isolation of a chymotryptic overlap peptide. The complete sequence of the 374 residues of actin is presented.

Actins↗
PubMed1975

The primary structure of actin from rabbit skeletal muscle. Three cyanogen bromide peptides that are insoluble at neutral pH.

Three of the 17 peptides produced when actin is treated with cyanogen bromide are sparingly soluble at pH values near neutrality. They were separated from more soluble peptides at pH 6.0 on a column of Sephadex G-10. The soluble peptides were excluded from the gel and emerged at the void volume, while the insoluble peptides were "washed off" by the formic acid in which the sample was applied. The three insoluble peptides were sequenced as a group by studying peptides generated by tryptic and chymotryptic digestion of the mixture, and peptic digestion of the partially resolved peptides. The three peptides are: CB-15 (residues 133 to 176), CB-16 (residues 325 to 354), and CB-17 (residues 191 to 227).

Actins↗
PubMed1975

Reconstitution of the Escherichia coli pyruvate dehydrogenase complex.

The binding of pyruvate dehydrogenase and dihydrolipoyl dehydrogenase (flavoprotein) to dihydrolipoyl transacetylase, the core enzyme of the E. coli pyruvate dehydrogenase complex [EC 1.2.4.1:pyruvate:lipoate oxidoreductase (decaryboxylating and acceptor-acetylating)], has been studied using sedimentation equilibrium analysis and radioactive enzymes in conjunction with gel filtration chromatography. The results show that the transacetylase, which consists of 24 apparently identical polypeptide chains organized into a cube-like structure, has the potential to bind 24 pyruvate dehydrogenase dimers in the absence of flavoprotein and 24 flavoprotein dimers in the absence of pyruvate dehydrogenase. The results of reconstitution experiments, utilizing binding and activity measurements, indicate that the transacetylase can accommodate a total of only about 12 pyruvate dehydrogenase dimers and six flavoprotein dimers and that this stoichiometry, which is the same as that of the native pyruvate dehydrogenase complex, produces maximum activity. It appears that steric hindrance between the relatively bulky pyruvate dehydrogenase and flavoprotein molecules prevents the transacetylase from binding 24 molecules of each ligand. A structural model for the native and reconstituted pyruvate dehydrogenase complexes is proposed in which the 12 pyruvate dehydrogenase dimers are distributed symmetrically on the 12 edges of the transacetylase cube and the six flavoprotein dimers are distributed in the six faces of the cube.

Acetyltransferases↗
PubMed1973

Complete amino-acid sequence of actin of rabbit skeletal muscle.

The complete amino-acid sequence of actin of rabbit skeletal muscle was determined. The actin polypeptide chain is composed of 374 residues, including one residue of the unusual amino acid N(r)-methyl histidine, and has a calculated molecular weight of 41,785. The sequence of actin was determined by isolating the peptides produced by cleavage of the protein with cyanogen bromide, determining the sequence of these peptides, and establishing their order within the molecule. This study represents the first complete determination of the aminoacid sequence of a myofibrillar protein. Comparison of this sequence with peptides from actins isolated from different sources indicates that the sequence of actin is highly conserved.

Actins↗