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PubMed · 6350009

Red cell deformability.

J A Dormandy
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Abstract

Deformation of red cells is an essential quality necessary for normal circulation. It can best be assessed by filtration techniques and these have revealed marked abnormalities in patients with cerebral ischemia. Whatever the exact pathological process involved, therapy aimed at normalizing red cell deformability may well be a successful approach to the treatment of cerebral ischemia.

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Adenosine DiphosphateAdenosine TriphosphateBrain IschemiaCerebrovascular CirculationErythrocytesFiltrationHematologyHumansMicrocirculationRheologySpectrinJournal ArticleReview

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J A Dormandy. 1983. Red cell deformability.. https://doi.org/10.1159/000115607

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Adenosine Diphosphate↗
PubMed1995

A 35-A movement of smooth muscle myosin on ADP release.

Myosin II crossbridges interact with F-actin producing powerstrokes of around 100 A (refs 1, 2), during which the products of ATP hydrolysis are released. This has been postulated to involve an articulation of the myosin head (S1) on actin, or substantial conformational changes in S1 itself. Small movements of the regulatory light chain have been detected (see, for example, refs 9, 10), but most data suggest that the bulk of S1 does not move on actin during crossbridge cycling. Here we present three-dimensional maps of S1-decorated F-actin in the presence and absence of MgADP. The myosin motor domain is similar in both states but there are major orientational differences in the light-chain-binding domain. This domain acts as a rigid level arm pivoting about the end of the motor domain and swinging approximately 23 degrees, resulting in a approximately 35-A step. Small, nucleotide-mediated conformational changes in the motor domain may thus be converted by the light-chain domain into large movement steps.

Adenosine Diphosphate↗
PubMed1995

Proton NMR investigation of the [4Fe--4S]1+ cluster environment of nitrogenase iron protein from Azotobacter vinelandii: defining nucleotide-induced conformational changes.

This work presents the complete assignment of the isotropically shifted 1H NMR resonances of Azotobacter vinelandii nitrogenase iron protein (Fe protein) to beta-CH2 and alpha-CH protons of the [4Fe--4S]1+ cluster cysteinyl ligands. Four resonances were observed for the reduced Fe protein with chemical shifts of 49, 23, 17, and 13 ppm. T1 measurements and analysis of relative peak areas coupled with one-dimensional nuclear Overhauser effect (NOE) difference spectra were used to assign the two most downfield-shifted resonances (49 and 23 ppm) to cysteinyl ligand beta-CH2 protons and the 17 and 14 ppm resonances to cysteinyl ligand alpha-CH protons. Temperature dependent studies of the isotropically shifted protons revealed both Curie and anti-Curie behavior. These results, along with previous Mossbauer studies of the Fe protein, allowed the assignment of signal A (49 ppm) to four beta-CH2 protons and signal C (17 ppm) to 2 alpha-CH protons of two cysteinyl ligands bound to a mixed-valence iron pair (Fe3(+)--Fe2+) of the [4Fe--4S]1+ cluster. Signal B (23 ppm) was assigned to four beta-CH2 protons, and signal C (17 ppm) and D (13 ppm) were assigned to two alpha-CH protons of two cysteinyl ligands bound to a ferrous pair of irons (2Fe2+). The effects of MgATP, MgADP, and Mg-adenosine-beta, gamma-methylene-5'-triphosphate binding to the Fe protein on the assigned resonances were established and are discussed in the context of nucleotide-induced changes in the protein environment of the [4Fe--4S] cluster.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗