Search PubMed⌕ Search

Biomedical subjects

B Walter

Publications and source records attributed to B Walter.

At least 127 records · Page 7Linked to original sources
PubMed1978

Studies on the differential inhibition by azide on the nitrite/nitrous oxide level of denitrification.

A gas chromatographic method was used to demonstrate that nitrite can counteract the inhibition by azide of nitrous oxide reductase activity in denitrifiers. This effect explains why azide (and cyanide) can inhibit nitrogen production from nitrous oxide in these organisms but have little effect on nitrogen production from nitrite. Although the physiological basis by which nitrite opposes the action of azide remains unknown, extensive destruction of azide by nitrite can be ruled out as an explanation.

Azides↗
PubMed1976

Characterization of agarose-bound trypsin.

Agarose-bound trypsin (EC 3.4.21.4) was prepared and its properties were compared with those of soluble trypsin. The bound form of the enzyme was found to be equally available to large and small molecular weight substrates as the soluble form. In addition, the bound form of the enzyme showed the same specificity towards protein substrates as the soluble enzyme. However, the agarose-bound trypsin showed greater stability than the soluble trypsin to denaturing conditions for prolonged period of time.

Caseins↗
PubMed1976

The role of lysine in the action of bovine pancreatic ribonuclease A.

The involvement of lysine residues in the active site of pancreatic ribonuclease has been investigated by assessing (a) the degree of substrate and substrate analogue protection of individual lysine residues against acetylation, and (b) the individual contribution of remaining unacetylated lysine residues to the total catalytic activity of the enzyme. Different substrate analogues (RNA digest, CMP, ATP, and pyrophosphate) were found to give different degrees of protection against acetylation with acetic anhydride. Instead of the expected specific protection of active site lysine residues such as lysine-7 and lysine-41, however, a general decrease in reactivity of all the lysines was observed when the substrate analogues were present during the acetylation. The fraction of enzymatic activity remaining in the protected samples was consistently greater than the fraction of any one lysine remaining unacetylated, and was found to correspond fairly well with the sum of the fractions of unacetylated lysine-7, lysine-41, and a third residue, tentatively assigned as lysine-66. This is consistent with other observations of ribonuclease which suggest that while no lysine residue interacts with substrate and substrate analogues in the formation of the Michaelis-Menten complex, a lysine amino group is required for catalysis. It is proposed that this lysine amino group can be supplied by any one of two or three lysine residues (7, 41, and 66) located close to the substrate binding site.

Acetates↗
PubMedDate not supplied

GAPO syndrome: a new case of this rare syndrome and a review of the relative importance of different phenotypic features in diagnosis.

The case of GAPO syndrome reported here is the 24th recorded case, 23 cases having been published previously. The 29-year-old male under discussion presents all the typical features of the syndrome, having short stature, dysmorphic craniofacial features, total alopecia and pseudoanodontia. Orally, the erupted primary dentition was extremely worn and on radiographic examination, the second mandibular molars were found to be unerupted, together with the entire permanent dentition. Cephalometry revealed the absence of facial pneumatisation, a deficient cranial base with diminished upper face height and maxillary and mandibular hypoplasia with a prognathic skeletal pattern. Histological examination of an extracted primary incisor and its surrounding root bone revealed extensive ankylosis. This paper describes in detail the clinical findings and reviews, and discusses previously published cases in relation to the present one. As with prior cases, parental consanguinity was present in the pedigree.

Abnormalities, Multiple↗