摘要:

AbstractMany bio‐inorganic reactions, especially of magnesium and calcium, take place in small vesicles. Chemistry in such small volumes has not been studied. Here we start an exploration of reactions in vesicles in order to understand the biological mechanism for the production of solids‐Such as bone. At the same time this study has generated new observations about inorganic reactions in small spaces. The products of reaction can be designed to provide new probes in electron microscopy and NMR spectroscopy or to carry drugs to locati

ISSN:0021-2148    

DOI:10.1002/ijch.198100002

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe phases for the x‐ray data for crystals of azurin fromP. aeruginosahave been refined and extended from 3 Å to 2.7 Å resolution by a method based on the direct space averaging of the electron density of the four molecules in the asymmetric unit. The electron density in the present map is much improved over the earlier one, and most of the side‐chains are now evident. In the detailed fitting of a model to the present map, an alternative interpretation, conforming to the plastocyanin model and reversing the chain directions in strands one and two of the original azurin model, was found to better represent certain features of the present map. The surface of the molecule closest to the copper consists of an extended region of invariant or semiconserved hydrophobic residues. There is not a region of conserved charge that is not paired with a compensating c

ISSN:0021-2148    

DOI:10.1002/ijch.198100003

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractPseudomonas aeruginosaazurin is stoichiometrically reduced by chromium (II) ions to yield a relatively inert chromium (III) complex with azurin. When this derivative is proteolytically digested by either trypsin or chymotrypsin, only a single, yet different peptide labeled with chromium is obtained upon chromatographic separations. Amino acid analysis of these fragments shows that the tryptic peptide consists of residues Val‐80 to Lys‐92, while the chymotryptic peptide consists of the Thr‐84 to Val‐95 fragment. Based on the above findings, the chemical nature of the amino acid side chains of these peptides and the crystallographic model of azurin, it is suggested that the chromium is coordinated to Lys‐85 and Glu‐91. This assignment and the analysis of the three dimensional model of azurin serve in delineating an electron transfer pathway. A resonance transfer from an opening in the peptide sheath to Cu(II) through an extended relay of the aligned imidazoles of His‐35 and His

ISSN:0021-2148    

DOI:10.1002/ijch.198100004

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe poor gastrointestinal absorption of inorganic chromium has hampered study of the bioavailability, biodistribution and function of this essential trace element. New coordination compounds of Cr(III) — most notably the Schiff base complexes of pyridoxal, dipeptides and nicotinic acid — have been synthesized and characterized for metabolic studies in mice. Data are presented to document the whole‐body absorption, excretory pathways and organ distribution of orally administered51Cr complexes. These compounds are well absorbed but retention is low because of rapid urinary excretion. The liver accumulates more Cr from the pyridoxylidene complexes than from inorganic or other coordination compounds. These results suggest that Schiff base chelates potentiate the absorption of Cr by cells of the intestine, kidney and liver. Coordination by nicotinic acid increased the stability of the Schiff base chelates but did not affect the biodistribution significantly. The relationship of these complexes to the “glucose tolerance factor” is

ISSN:0021-2148    

DOI:10.1002/ijch.198100005

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe nickel(II) derivative ofRhus verniciferastellacyanin has been prepared. The near‐infrared, visible, and near‐ultraviolet absorption spectra of the nickel(II) derivatives of stellacyanin andPseudomonas aeruginosaazurin are reported. Charge transfer bands in the visible and near‐ultraviolet regions are assigned as follows: nickel(II)‐stellacyanin, 335 nm (29,900 cnr−1) (πN(his)→Ni(II)), 410 nm (24,400 cm−1) (σS(cys) → Ni(II)), and 470 nm (21,300 cm−1)(πS(cys)→ Ni(II)); nickel(II)‐azurin, 355 nm (28,200 cm−1) (πN(his)→Ni(II)), 440 nm (22,700 cm−1) (σS(cys)→ Ni(II)), and 500 nm (20,000 cm−1) (πS(cys)→ Ni(II)). Relatively weak bands at 550 (18,200) and 590 nm (16,900 cm−1) (Ni(II)St) and 540 (18,500) and 565 nm (17,700 cm−1) (Ni(II)Az) are attributed to d–d excitations. No evidence for lower energy d‐d bands has been found for either Ni(II)–protein. The data now in hand raise the possibility that the Ni(II) site structure differs from the flattened tetrahedr

ISSN:0021-2148    

DOI:10.1002/ijch.198100006

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractA brief review is given of the available methods for removing the Type 2 Cu from blue oxidases and of the properties of the modified enzymes. The Type 2 Cu appears to be essential to the catalytic activity of the enzymes and to participate, at least in tree laccase, both in the reductive and oxidative processes. The Type 2 Cu is also involved in water exchange with bulk solution and in the binding of anions and of H2O2. It is connected with the other copper types, as its removal considerably affects their redox potential and the intensity of the 330 nm charge transfer band associated with a two‐electron accepto

ISSN:0021-2148    

DOI:10.1002/ijch.198100007

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.198100008

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.198100009

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe production of zinc protoporphyrin by the erythrocyte has been shown to be a good indicator of lead intoxication. The relationship between zinc protoporphyrin levels in blood and lead‐induced anemia are examined. Serum iron parameters show that the anemia is not related to the lack of availability or transport of iron, but to faulty utilization by the reticulocyte. Although zinc protoporphyrin is produced in response to both lead intoxication and iron deficiency, it is pointed out that plasma iron and lead levels provide a method for differentiating between the

ISSN:0021-2148    

DOI:10.1002/ijch.198100010

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractAngiotensin converting enzyme is a chloride‐dependent zinc metalloexo‐peptidase. The zinc atom is essential for enzymatic activity. Removal of zinc by dialysis against the chelating agent 1,10‐phenanthroline abolishes activity toward the chromophoric substrates furanacryloyl‐Phe‐Gly‐Gly. Reconstitution of the resultant apoenzyme with either zinc, cobalt or manganese restores activity to 100, 55 or 25% of that of the native enzyme, respectively. Spontaneous dissociation of zinc from the enzyme occurs below pH 7 and this can be prevented by adding excess metal to the buffer. Radiationless energy transfer studies with a fluorescent substrate demonstrate that zinc is not required for substrate binding and does not mediate the activating effect of chloride. Thus, zinc functions solely in the hydrolytic step o

ISSN:0021-2148    

DOI:10.1002/ijch.198100011

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY