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W M Holmes

Publications and source records attributed to W M Holmes.

42 records · Page 3Linked to original sources
PubMed1974

Homologous and hybrid complexes of anthranilate synthase from Bacillus species.

The subunits of anthranilate synthase were separated and partially purified by Sephadex G-100 gel filtration from the following six species of Bacillus: Bacillus subtilis, Bacillus licheniformis, Bacillus alvei, Bacillus coagulans, Bacillus pumilus, and Bacillus mascerans. Our data suggest that the enzyme from B. alvei is unique among these species. First, the anthranilate synthase complexes are readily dissociated during gel filtration in the absence of glutamine into a large component (aminotransferase), subunit E, and a small component subunit X (glutamine-binding protein), whereas a higher salt concentration is required to dissociate the complex from B. alvei. Second, the aminotransferase activity from all six species is stimulated by glycerol and inhibited by tryptophan; however, only the large component from B. alvei is stimulated by 2-mercaptoethanol. Finally, the large component can be titrated with the small component to yield a complex which can utilize glutamine as a substrate (amidotransferase). The homologous complexes have an amidotransferase to aminotransferase ratio of 1.4 to 2.3, but the B. alvei complex has a ratio of 0.9. Except for complexes that involve the large component from B. alvei, hybrid complexes can be formed which have ratios as good as the homologous complexes. These data are consistent with the hypothesis that B. alvei is unique among the bacilli with respect to some enzymes in the aromatic amino acid biosynthetic pathway.

Amides↗
PubMed1973

Intergeneric complementation of anthranilate synthase subunits.

Partially purified subunits of anthranilate synthase were prepared from Bacillus subtilis and Pseudomonas aeruginosa. The large component from B. subtilis (I(B)) complements well with the small component from P. aeruginosa (II(P)) to reconstitute a glutamine-reactive anthranilate synthase. This interaction can be demonstrated with crude extracts from a B. subtilis trpX mutant and a P. aeruginosa trpA mutant. Complementation was also observed with the large component from P. aeruginosa (I(P)) and the small subunit from B. subtilis (II(B)). At saturation the heterologous complex I(B)II(P) has 93% of the activity of the homologous complex I(B)II(B), whereas the hybrid I(P)II(B) is only 22% as active as the homologous complex I(P)II(P).

Ammonia↗
PubMedDate not supplied

Rapid method for altering bacterial ribosome-binding sequences for overexpression of proteins in Escherichia coli.

In an Escherichia coli expression system, two genes, one from an anaerobic intestinal bacterium and one from E. coli, were overexpressed following the alteration of ribosome-binding (Shine-Dalgarno) sequences. For both genes, the polymerase chain reaction (PCR) was used to modify the ribosome-binding sequence and, at the same time, provide restriction endonuclease sequences at each end of the gene. These restriction endonuclease sequences were used for inserting the DNA into the E. coli plasmid vector pGEM2, which has the T7 promoter upstream from its multiple cloning sites. Each chimeric plasmid, made by ligating the PCR product into pGEM2, was transformed into E. coli strain HMS174(DE3) which, when induced, produces T7 RNA polymerase for regulated overexpression. The gene isolated from the anaerobic intestinal bacterium, a 27-kDa polypeptide gene from Eubacterium sp. strain 12708, when expressed using this system, produced about one-third of the total cell protein as measured in Coomassie-stained protein gels and confirmed by Western blots with rabbit antibody. The E. coli enzyme, a 28.4-kDa tRNA methylation enzyme, was increased fivefold in activity of cell extracts over that of the best previous strain.

Bacterial Proteins↗
PubMedDate not supplied

Diffusion in thin films on the surface of a porous solid.

A water-wet mono-dispersed glass bead system is saturated with two phases, a wetting phase of water and a non-wetting phase of tetrachloroethylene (no 1H signal). Pulsed field gradient NMR measurements of the one-dimensional probability density distribution P(Delta) (X) for the diffusive displacements of water molecules in times, Delta, are presented for the whole accessible water saturation range. At lower water contents the distributions show a distinctive shape, which is attributed to the distribution of the aqueous phase in thin surface wetting films connecting pendular rings where the beads are in contact. The data are reproduced well by a computer simulation of a random walk model based on diffusion of molecules within such a structure, allowing determination of the surface film thickness.

Diffusion↗
PubMedDate not supplied

Evaluating the treatment of emotionally disturbed adolescents.

The authors designed a scale, the Massachusetts Adolescent Level of Functioning Scale, for measuring the behavior of emotionally disturbed adolescents. Among the many uses of the scale are specifying a standard intervention for any given problem indicator and measuring the outcome. A pilot test demonstrated that the scale has broad applications for determining cost-effectiveness of programs and for improving service delivery.

Adolescent↗