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Biomedical subjects

Y Lapidot

Publications and source records attributed to Y Lapidot.

At least 19 recordsLinked to original sources
PubMed1998

Relief from job stressors and burnout: reserve service as a respite.

To reveal the ameliorative impact of being away from job stressors on burnout, we compared 81 men who were called for active reserve service with 81 matched controls in the same company who were not called during the same period. Each reservist and his control completed questionnaires shortly before the reservist left work for a stint of service and immediately on his return. Analysis of variance detected a significant decline in job stress and burnout among those who served and no change among the control participants. Among those who served, quality of reserve service and degree of psychological detachment from work interacted in moderating the respite effects; the greater the detachment, the stronger the effect positive reserve service experience had in relieving reservists from stress and burnout. Reserve service is discussed as a special case of stress-relieving get-away from work that may be experienced as an ameliorative respite akin to vacation.

Adult↗
PubMed1977

CD studies on ribonuclease A - oligonucleotides interactions.

The interaction of ApU, Aps4U, Aps4Up, ApAps4Up and Gps4U with RNase A was studied by CD difference spectroscopy. The use of 4-thiouridine (s4U) containing oligonucleotides enables to distinguish between the interaction of the different components of the ligand with the enzyme. The mode of binding of the oligonucleotides to the enzyme is described. From this mode of binding it is explained why Aps4U, for example, inhibits RNase A, while s4UpA serves as a substrate.

Binding Sites↗
PubMed1977

Inhibition of pancreatic ribonuclease by 2'-5' and 3'-5' oligonucleotides.

Forty different oligonucleotides were investigated as possible inhibitors of the depolymerizing activity of RNase A. The strongest inhibitors among the diribonucleoside 2'-5' mono- phosphates were: G2'-5'G, C2'-5'G and U2'-5'G, and among the diribonucleoside 3'-5' monophosphates: ApU, ApC and GpU. Of the eight trinucleotides investigated, ApApUp, ApApCp and ApGpUp were the strongest inhibitors. All four dinucleotides studied (ApUp, ApCp, GpUp and GpCp) were very strong inhibitors, ApUp being the strongest one. The results show that the nature of the various bases in the oligonucleotide has an effect on the degree of inhibition, and that the 3' phosphomonoester group increases the binding of the oligonucleotide to RNase A. These inhibitors can be used in physicochemical and biochemical studies of ribonuclease.

Kinetics↗
PubMed1975

The influence of the peptide chain length on the activity of peptidyl-tRNA hydrolase from E. coli.

The dependence of the Vmax and Km on the length of the peptide moiety in the peptidyl-tRNA series (Gly)n-Val tRNA, was measured in the system peptidyl-tRNA hydrolase-peptidyl-tRNA. It was found that the Km value decreases from 7.2 X 10-7 M for Gly-Val-tRNA to 4.6 X 10-7 M FOR (Gly)2-Val-tRNA and to 1.7 X 10-7M for (Gly)3-Val-tRNA; further increase of the peptide chain is not followed by decrease of the Km. The Vmax values are 5.7 pmole/min/EU for Gly-Val-tRNA and 42 pmole/min/EU for (Gly)3-Val-tRNA. The enzyme activity is inhibited competitively by uncharged tRNA with a KI value of about 10-5M. The significance of these results described in this paper, in relation to the fact that peptides and peptide esters do not inhibit the enzyme activity, and in relation to the proposed physiological role of the enzyme, is discussed.

Carboxylic Ester Hydrolases↗
PubMed1975

Purification of peptidyl-tRNA on benzoylated DEAE-cellulose columns.

The o-nitrophenylsulfenyl group, and amino protecting group in the chemical synthesis of peptidyl-tRNA was used to attach newly synthesized peptidyl-tRNA to a benzoylated DEAE-cellulose column. This facilitated the isolation of a highly purified specific tRNA with a well defined peptide chain.

Chromatography, DEAE-Cellulose↗