The origin of histamine bound in certain mammalian tissues, in which it is available for release in such conditions as tissue damage and anaphylactic shock, has not been conclusively demonstrated. It has been postulated that it arises either from dietary histidine or from exogenous histamine formed in the intestine or in tissues high in histidine decarboxylase (1). Increases, of brief duration,...

It is well known that histidine is involved in many biological functions due to the structural versatility of its side chain. However, probing the conformational transitions of histidine in proteins, especially those occurring on an ultrafast time scale, is difficult. Herein we show, using a histidine dipeptide as a model, that it is possible to probe the tautomer and protonation status of a hi...

Histidine occurs widely in nature both in the free and combined form. In order to study histidine in its various roles it is necessary therefore to have a sensitive and specific method for its estimation. The colorimetric method described initially by Pauly (1904) and since modified by various workers (Koessler & Hanke, 1919; Jorpes, 1932; Macpherson, 1942; Sanger & Tuppy, 1951), which depends ...

It has previously been shown that the enzymes that catalyze the first two steps, L-histidine ammonia-lyase and urocanase, are induced by L-histidine and repressed by catabolites (4, 5). It will be shown in the present paper that the enzyme catalyzing the fourth step of the sequence, N-formimino-r-glutamate formiminohydrolase, is also subject to induction by n-histidine and repression by catabol...

KCa2.1, KCa2.2, KCa2.3 and KCa3.1 constitute a family of mammalian small- to intermediate-conductance potassium channels that are activated by calcium-calmodulin. KCa3.1 is unique among these four channels in that activation requires, in addition to calcium, phosphorylation of a single histidine residue (His358) in the cytoplasmic region, by nucleoside diphosphate kinase-B (NDPK-B). The mechani...

OBJECTIVE Cerebrospinal fluid (CSF) leaks may present as rhinorrhea or otorrhea and can lead to life-threatening complications if not detected. The usefulness of the morpholinopropanesulfonic acid (MOPS)-histidine buffer in detecting β₂-transferrin, which is only found in the cerebrospinal fluid, was compared with the standard barbital buffer. METHODS We evaluated 20 aural or nasal patient sp...

MtATP-phosphoribosyltransferase catalyzes the first and committed step in l-histidine biosynthesis in Mycobacterium tuberculosis and is therefore subjected to allosteric feedback regulation. Because of its essentiality, this enzyme is being studied as a potential target for novel anti-infectives. To understand the basis for its regulation, we characterized the allosteric inhibition using gel fi...

The initiation of sporulation in Bacillus species is regulated by the phosphorelay signal transduction pathway, which is activated by several histidine sensor kinases in response to cellular and metabolic signals. Comparison of the protein components of the phosphorelay between Bacillus subtilis and Bacillus anthracis revealed high homology in the phosphorelay orthologs of Spo0F, Spo0B, and Spo...

BACKGROUND The purpose of this study was to compare the myocardial protective effect of histidine-tryptophan-potassium and glucose-insulin-potassium cardioplegic solutions in patients with a dilated heart (left ventricular diastolic diameter > 55 mm, left ventricular systolic diameter > 45 mm) associated with prolonged cross-clamp time (longer than 200 minutes). METHODS We selected 20 patient...

Most paramyxovirus fusion proteins require coexpression of and activation by a homotypic attachment protein, hemagglutinin-neuraminidase (HN), to promote membrane fusion. However, the molecular mechanism of the activation remains unknown. We previously showed that the incorporation of a monohistidylated lipid into F-virosome (Sendai viral envelope containing only fusion protein) enhanced its fu...