PubMed Health⌕ Search

Biomedical subjects

T Ashida

Publications and source records attributed to T Ashida.

At least 145 records · Page 8Linked to original sources
PubMed1987

The structure of Bowman-Birk type protease inhibitor A-II from peanut (Arachis hypogaea) at 3.3 A resolution.

The structure of Bowman-Birk type protease inhibitor (A-II from peanut) is described at 3.3 A resolution. The molecules form a tetramer with 222 local symmetry in our crystals. Each monomer has an elongated shape with approximate dimensions of 45 X 15 X 15 A and consists of two distinct domains. The three-dimensional structures of the two domains are similar and are related by the intramolecular approximate twofold rotation axis. The two independent protease binding sites protrude from the molecular body on opposite sides. A scheme for the molecular evolution of the double-headed Bowman-Birk type protease inhibitors is proposed, based on the three-dimensional structure.

Arachis↗
PubMed1986

A role for Lyb-2 in B cell activation mediated by a B cell stimulatory factor.

The Lyb-2 system of the mouse is involved in regulation of a proliferative step in the differentiation of B cells responding to T-dependent antigen. The present study concerns the role of Lyb-2 in an early phase of B cell activation with respect to B cell receptor functions for activation factors. It is shown that interaction of monoclonal anti (alpha)-Lyb-2 antibody with Lyb-2 on the B cell surface induces B cell proliferation by synergistic action with B cell growth factor II-containing factor or interleukin 1. In contrast, alpha-Lyb-2 antibody could not synergize with the Con A-induced culture supernatant of T cell hybridoma FS6-14.13 (FS6) containing B cell stimulatory factor-1 (BSF-1; formerly called BCGF I), and the effect of combining the two was only additive on B cell proliferation. Absorption studies showed that BSF-1 in FS6 could be absorbed by unstimulated B cells, about 95% of which were at Go phase of the cell cycle, but not by thymocytes, and more importantly that alpha-Lyb-2 antibody blocked the absorption in an Lyb-2-specific manner, possibly by competing with BSF-1. It is thus likely that alpha-Lyb-2 antibody may interact with a BSF-1 receptor on B cells or a molecule closely associated with it. Interestingly, alpha-Lyb-2 antibody mimicked the action of BSF-1 in a costimulator assay with affinity-purified goat alpha-mouse IgM antibody, but could not replace all the activities ascribed to BSF-1. Possible mechanisms involved are discussed.

Animals↗
PubMed1986

Crystallization of Bowman-Birk type protease inhibitor (peanut) and its complex with trypsin.

Crystallization and preliminary crystallographic study of Bowman-Birk type protease inhibitors, A-I, A-II, and B-III from peanut seeds (Arachis hypogaea), and of the A-II + trypsin complex were carried out. A-II, with 70 amino acid residues, crystallizes in a trigonal system, P3(1)21 (or P3(2)21), a = 71.8, c = 65.9 A, Z = 12 or 18. The A-I crystal is isomorphous with that of A-II, indicating that the N-terminal residues are in a disordered state in both crystals. The B-III crystal is monoclinic, C2, a = 119.6, b = 69.6, c = 94.2 A, beta = 115.1 degrees, Z is about 40. The A-II + trypsin complex crystallizes in an orthorhombic system, P2(1)2(1)2(1), a = 55.5, b = 56.0, c = 182.1 A, Z = 4.

Arachis↗
PubMed1986

Structure of the trypsin-binding domain of Bowman-Birk type protease inhibitor and its interaction with trypsin.

The crystal structure of the complex formed by bovine trypsin and Bowman-Birk type protease inhibitor AB-I extracted from azuki beans (Vigna angularis) 'Takara' has been analyzed. The structure was solved by the application of the phase combination of single isomorphous phases and trypsin model phases, followed by phase improvement using the iterative Fourier technique. From the resulting electron density map, a three-dimensional atomic model of the trypsin binding domain of AB-I has been built. The peptide chain at the trypsin reactive site turns back sharply at Pro29 and forms a 9-residue ring (Cys24-Cys32). The 'front side' of this ring, consisting of the reactive site (Cys24-Met28), interacts with trypsin in a similar manner to other families of inhibitors and forms a stable complex, which seems to be maintained by the interactions with the 'back side' of this ring (Pro29-Cys34). The similar spatial arrangements of the 'back side' of this inhibitor and the 'secondary contact region' of the other inhibitors with respect to the reactive site suggest an important common role of these regions in exhibiting inhibitory activity.

Chemical Phenomena↗
PubMed1984

Vasopressin as a possible contributor to hypertension.

The role of vasopressin as a pressor agent to the hypertensive process was examined. Vasopressin plays a major role in the pathogenesis of DOCA-salt hypertension, since the elevation of blood pressure was not substantial in the rats with lithium-treated diabetes insipidus after DOCA-salt treatment. Administration of DDAVP which has antidiuretic action but minimal vasopressor effect failed to increase blood pressure to the levels observed after administration of AVP. Furthermore, the pressor action of vasopressin appears to be important in the development of this model of hypertension, since the enhanced pressor responsiveness to the hormone was observed in the initial stage of hypertension. Increased secretion of vasopressin from neurohypophysis also promotes the function of the hormone as a pathogenetic factor in hypertension. An unproportional release of vasopressin compared to plasma osmolality may be induced by the absence of an adjusting control of angiotensin II forming and receptor binding capacity for sodium balance in the brain. However, the role of vasopressin remains to be determined in human essential hypertension.

Animals↗
PubMed1983

Preliminary crystallographic study of Bowman-Birk protease inhibitor (adzuki bean) and its complex with trypsin.

Preliminary crystallographic studies of a Bowman-Birk type protease inhibitor, AB-I, from adzuki beans (Phaseolus angularis) 'Takara,' and its complex with trypsin were carried out. AB-I, MW 9100 with 82 amino acid residues, crystallizes in a trigonal space group, P3121 (or P3221), with the following unit cell dimensions: a = 68.7, c = 99.7 A. The asymmetric unit contains two dimer molecules. Structure analysis at 5 A resolution revealed the rough appearance of the dimer. The complex between AB-I and trypsin also could be crystallized in a tetragonal space group, P41212 (or P43212), with the unit cell dimensions, a = 55.4 and c = 181.5 A, and Z = 8. The crystallinity seems to be much better than that of the crystals of the inhibitor alone. The other type of inhibitor from adzuki bean, AB-IIa, was also crystallized.

Chemical Phenomena↗
PubMed1983

Normalizing effects of plasma on altered cation transport of red blood cells from essential hypertensive patients.

Net Na+ and K+ fluxes were measured in Na+-loaded red cells from 19 normotensive control subjects, 22 essential hypertensive patients, and 8 secondary hypertensive patients. The ratio of Na+/K+ net fluxes was significantly lower in essential hypertensive patients than in normotensive control subjects. However, by the addition of the patients' own plasma, the net Na+ efflux rate was significantly increased in essential hypertensive patients, which caused the increment in the ratio of Na+/K+ net fluxes. This resulted in disappearance of the difference between normotensive and hypertensive subjects in the ratio of cation fluxes. It was possible that the abnormalities of cation transport in red cells from essential hypertensive patients might be compensated for by humoral factors in the plasma.

Adolescent↗