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Biomedical subjects

L Grossman

Publications and source records attributed to L Grossman.

At least 127 records · Page 7Linked to original sources
PubMed1981

Enzymatic mechanisms of DNA repair.

DNA repair proficiency in cells is expressed by various enzymes which can recognize damaged sites arising from exogenous agents or endogenous conditions. Either a damaged base is recognized by DNA glycosylases, partially removed by hemi-DNA glycosylases acting on diadduct damage, or direct incision of the phosphodiester bond near the damaged site. Incision at those apurinic or apyrimidinic sites arising from depurination-depyrimidination or glycosylase reactions is effected by apurinic or apyrimidinic endonucleases. Excision of damaged sites is catalyzed by unique exonucleases followed by DNA polymerase catalyzed reinsertion of nucleotides. The integrity of the strands is restored by polynucleotide ligase when a juxtaposed nucleotide is properly reinserted.

Animals↗
PubMed1980

Cleavage of pyrimidine dimers in specific DNA sequences by a pyrimidine dimer DNA-glycosylase of M. luteus.

Pyrimidine dimer formation in response to UV radiation is governed by the thymine content of the potential dimer and the two flanking nucleotides. An enzymatic activity can be purified from Micrococcus luteus that cleaves the N-glycosyl bond between the 5' pyrimidine of a dimer and the corresponding sugar without rupture of a phosphodiester bond. We propose that strand scission at a dimer site by the M. luteus enzyme requires two activities, a pyrimidine dimer DNA-glycosylase and an apyrimidinic/apurinic endonuclease.

Apurinic Acid↗
PubMed1980

Isolation of plasmids carrying either the uvrC or uvrC uvrA and ssb genes of Escherichia coli K-12.

A 3.4 kb PstI fragment containing the uvrC gene of Escherichia coli K-12 has been cloned into pBR322. Plasmids carrying this PstI fragment, in either orientation (pGY3233, pGY4211) relative to the cloning vehicle, complement uvrC mutants. A second plasmid (pGY3243) with a 21 kb HindIII fragment is shown to complement mutations in uvrA and ssb (single-strand binding protein). A composite plasmid (pGY4610) containing pBR322 and PstI fragments derived from pGY3233 (3.4 kb) and pGY3243 (11.05 kb) complements the uvrC, uvrA and ssb mutations.

Cloning, Molecular↗
PubMed1979

Changing hospital practice and social work staffing.

If social workers are to survive in hospitals and gain satisfacation from their work, they must begin to find new ways to apply their skills. This article analyzes several factors affecting the health care industry and suggests that staffing a hospital social work department follow a situational rather than a universal approach.

Hospital Departments↗
PubMed1977

Micrococcus luteus correndonucleases. II. Mechanism of action of two endonucleases specific for DNA containing pyrimidine dimers.

Py pyrimidine dimers Py correndonucleases I and II from Micrococcus luteus act exclusively on thymine-thymine, cytosine-cytosine, and thymine-cytosine cyclobutyl dimers in DNA, catalyzing incision 5' to the damage and generating 3'-hydroxyl and 5'-phosphoryl termini. Both enzymes initiate excision of pyrimidine dimers in vitro by correxonucleases and DNA polymerase I. The respective incised DNAs, however, differ in their ability to act as substrate for phage T4 polynucleotide ligase or bacterial alkaline phosphatase, suggesting that each endonuclease is specific for a conformationally unique site. The possibility that their respective action generates termini which represent different degrees of single strandedness is suggested by the unequal protection by Escherichia coli binding protein from the hydrolytic action of exonuclease VII.

Alkaline Phosphatase↗
PubMed1977

Micrococcus luteus correndonucleases. I. resolution and purification of two endonucleases specific for DNA containing pyrimidine dimers.

Five peaks of endonuclease activity showing a preference for ultraviolet-damaged DNA have been chromatographically identified from extracts of Micrococcus luteus. They are numerically designated as I to V in order of their elution from phosphocellulose (Whatman P-11) columns. The first two of these peaks have been highly purified by a combination of gel filtration and affinity chromatography and are catalytically homogeneous judging from their effect on transforming DNAs. Peak I, which has an isoelectric point of 4.7, is heat-stable, requires high ionic strength for optimal activity, acts with equal facility on ultraviolet-irradiated native and denatured DNA, and has been designated as Py pyrimidine dimer Py correndonuclease I. Peak II which has a pI value of 8.7, is heat-labile, is inhibited by high ionic strength, acts on ultraviolet-irradiated native but not denatured DNA, and has been designated as Py pyrimidine dimer Py correndonuclease II. Both enzymes are inhibited by Ca2+ and Zn2+, do not show any cofactor or sulfhydryl requirement, act optimally between pH 7.0 and 7.4, and have molecular weights between 11,000 and 15,000. Py pyrimidine dimer Py correndonuclease I requires a dose about 1.6 times that for Py pyrimidine dimers Py correndonuclease II for incision saturation of irradiated phiX174 RFI DNA.

Chromatography, Gel↗