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Biomedical subjects

R W Carrell

Publications and source records attributed to R W Carrell.

At least 181 records · Page 10Linked to original sources
PubMed1977

Oxidation of human haemoglobin by copper. Mechanism and suggested role of the thiol group of residue beta-93.

Addition of Cu(II) ions to human oxyhaemoglobin caused the rapid oxidation of the haem groups of the beta-chain. Oxidation required binding of Cu(II) to sites involving the thiol group of beta-93 residues and was prevented when these groups were blocked with iodoacetamide or N-ethylmaleimide. Equilibrium-dialysis studies showed three pairs of binding sites, two pairs with high affinity for Cu(II) and one pair with lower affinity. It was the second pair of high-affinity sites that were blocked with iodoacetamide and were involved in haem oxidation. Cu(II) oxidized deoxyhaemoglobin at least ten times as fast as oxyhaemoglobin, and analysis of rates suggested that binding rather than electron transfer was the rate-determining step. No thiol-group oxidation to disulphides occurred during the period of haem oxidation, although it did occur subsequently in the presence of oxygen, or when Cu(II) was added to methaemoglobin. It is proposed that thiol oxidation did not occur because there exists a pathway of electron transfer between the haem group and copper bound to the beta-93 thiol groups. The route for this electron transfer is discussed, as well as the implications as to the function of the beta-93 cysteine in the haemoglobin molecule.

Binding Sites↗
PubMed1977

A new hybrid haemoglobin: haemoglobin Strumica/Beograd occurring in an individual with four haemoglobins.

An investigation of the cord blood from full term twin infants revealed an additional haemoglobin F component due to an abnormal alpha chain. The father of the twins, whose blood picture was normal, was shown to have normal alpha and beta polypeptide chains together with variant alpha and beta polypeptide chains. Electrophoresis showed that he had four major haemoglobin components. Separation of the haemoglobin fractions by column chromatography, globin preparation, chain separation, tryptic and chymotryptic digestion and peptide map preparation led to the identification of haemaglobin A, haemoglobin Strumica (alpha2 112His leads to Arg beta2), haemoglobin D Beograd (alpha2beta2 121 Glu leads to Val) and a hybrid haemoglobin Strumica D/Beograd (alpha2 112His leads to Argbeta2 121Glu leads to Val).

Alleles↗
PubMed1977

Haemoglobin--a frustrated oxidase? Implications for red cell metabolism.

The haem proteins can be considered, in one aspect of their function, as machines for activating oxygen. In the case of oxygen-carriers such as haemoglobin, the globin has evolved so that its conformation limits access to the haem group, with resultant reversible release of oxygen. However, distortion of the globin may allow either the discharge of oxygen as the activated product superoxide or, more threateningly, allow direct function of the haemoglobin as an oxidative enzyme. Support for this is shown by the reaction with acetylphenylhydrazine where haemoglobin functions as both an oxidase and oxygenase. An implication of oxidase activity is the potential to initiate free radical formation particularly with unsaturated lipids. Observations of the acetylphenylhydrazine reaction emphasize the role of glutathione as a free radical scavenger.

Ascorbic Acid↗
PubMed1977

Isolation of high oxygen affinity hemoglobins.

This paper describes a method for isolating high oxygen affinity hemoglobins. It involves the selective derivatisation of the cysteine residue at position 93 in the beta chain. The iodoacetamide derivative of the high oxygen affinity hemoglobin was separated from the more negatively charged iodoacetic acid derivative of HbA on DEAE-Sephadex. The method was used to isolate two high oxygen affinity hemoglobins, one of which was subsequently identified as Hb Heathrow.

Amino Acid Sequence↗
PubMed1976

Reactions involving superoxide and normal and unstable haemoglobins.

Superoxide ions (O2-) oxidized oxyhaemoglobin to methaemoglobin and reduced methaemoglobin to oxyhaemoglobin. The reactions of superoxide and H2O2 with oxyhaemoglobin or methaemoglobin and their inhibition by superoxide dismutase or catalase were used to detect the formation of superoxide or H2O2 on autoxidation of oxyhaemoglobin. The rate of autoxidation was decreased at about 35% in the presence of both enzymes. The copper-catalysed autoxidation of Hb (haemoglobin) was also shown to involve superoxide production. Superoxide was released on autoxidation of three unstable haemoglobins and isolated alpha and beta chains, at rates faster than with Hb A. Reactions of superoxide with Hb Christchurch and Hb Belfast were identical with those with Hb A, and occurred at the same rate. Hb Koln contrasted with the other haemoglobins in that the thiol groups of residue beta-93 as well as the haem groups reacted with superoxide. Haemichrome formation from methaemoglobin occurred very rapidly with Hb Christchurch and Hb Belfast, as well as the isolated chains, compared with Hb A. The process did not involve superoxide production or utilization. The relative importance of autoxidation and superoxide production compared with haemichrome formation in the haemolytic process associated with these abnormal haemoglobins and thalassaemia is considered.

Copper↗
PubMed1976

Contributions of other sterols to the estimation of cholesterol.

The responses of 5alpha-cholestan-3beta-ol, 5alpha-cholest-7-ene-3beta-ol and cholesta-5,7-dien-3beta-ol, normally found in human serum, were examined by: (1) the Liebermann-Burchard reaction, (2) the Zak (ferric chloride) reaction, (3) an enzymatic cholesterol method monitored by estimating the amount of hydrogen peroxide produced, (4) an enzymatic cholesterol method monitored by observing the change in absorbance at 240 nm, and (5) gas chromatography. The results show that none of these methods is specific for cholesterol; contributions from the sterols examined range from zero to more than 150% relative to cholesterol. For the first four methods contributions depend on the conditions under which each test is performed.

Cholestadienols↗
PubMed1976

Homozygous cystinuria and the oculo-cerebro-renal dystrophy of Lowe in same family.

The mother and daughter in a family had homozygous cystinuria and were also heterozygous carriers of the oculo-cerebro-renal dystrophy of Lowe. The daughter was also epileptic. The son had Lowe's syndrome and the father an increased urinary excretion of cystine and lysine. This evidence together with other case reports suggests that the defect in cystinuria and that of Lowe's syndrome may be connected.

Abnormalities, Multiple↗
PubMed1975

Alpha-1-antitrypsin variants in New Zealand.

Twelve percent of a sample of New Zealand Europeans were found to have variant forms of alpha-1-antitrypsin. The distribution of different variants was similar to that found in other Northern European populations. Four percent were heterozygotes for the deficiency state (Z allele) which predisposes to both emphysema and cirrhosis. An initial survey of New Zealand Maoris suggests that although they have a lower overall incidence of variants, there is an increased frequency of the deficiency Z allele. This may be a contributory factor to the susceptibility of the Maori to respiratory and liver disease.

Adult↗
PubMed1975

The isolation and identification of haemoglobin Lephore Boston (Washington) in an Australian family.

Haemoglobin Lepore is a haemoglobin variant associated with a thalassaemia-like disorder. It has been only rarely detected in Anglo-Saxons and its occurrrence in an Australian family of British and stock is reported for the first time. The appearances of the blood film resemble those seen in various hypochromic anaemias, inclusing thalassaemia traits, and on this account it is of clinical importance to recognize it in order to avoid unnecessary investigation and treatment. The chemical structure of nine examples of haemoglobin Lepore has been confirmed by peptide mapping and amino acid analysis, and the genetic mechanisms postulated for the production of haemoglobin Lepore are discussed.

Amino Acids↗
PubMed1975

Obesity in a New Zealand community.

A retrospective analysis of the height, weight and certain biochemical data from the Rangiora Diabetic Survey is presented. In this survey 93 percent of the 2670 adult Europeans in Rangiora were studied. A high prevalence of obesity was found with 31 percent of the men and 46 percent of the women being greater than 20 percent above their ideal body weight. More than half the women aged 50 years and over were obese by the criteria used. The peak prevalence of obesity was in the seventh decade for women and in the eighth and ninth decades for men. There were significant increases in serum uric acid in obese men and women in each age decade. A surprise finding in the obese men was the increase in plasma protein levels but this did not occur in the obese women. Both men and women had a trend towards higher blood sugars when obese.

Adult↗
PubMed1975

Haemoglobin Camperdown beta104(G6) arginine leads to serine.

Routine investigation of ante natal patients revealed a subtle change in the electrophoretic pattern on cellulose acetate of the proposita. Further investigations by isoelectric focussing in polyacrylamide gel suggested the presence of two major haemoglobin components. Using a modified cellulose acetate technique globin chain separation revealed an abnormal beta-chain. Chain separation on a carboxymethyl-cellulose column provided a pure sample of the abnormal beta-chain. After amino-ethylation, tryptic digestion and peptide mapping, amino acid analysis of relevant peptides showed the abnormality in the beta-chain to be a substitution of arginine by serine at the 104 position. The presence of a positively charged residue at this position would appear to be necessary for the stabilization of the haemoglobin central cavity. The replacement by serine in this haemoglobin leads to slightly decreased stability but does not appear to affect the oxygen affinity.

Adult↗
PubMed1975

Alpha-1-antitrypsin deficiency in New Zealand.

A severe deficiency of the serum protein alpha-1-antitrypsin can be expected to occur in 1 in 750 European New Zealanders. It can usually be identified by a faint or absent alpha-1 band on serum protein electrophoresis. Forty-seven cases are presented. 31 phenotype ZZ and 16 phenotype SZ. Eighteen have developed emphysema usually by age 40 years, two show childhood liver disease. One adult died of liver disease and three of the emphysema patients had liver abnormalities at post mortem. The remainder, mainly aged less than 30 years, are as yet asymptomatic. Individuals at risk should be protected from respiratory irritants (cigarettes, dusty environments and chest infections) and liver toxins (e.g., alcohol). The partial deficiency state (MZ) which occurs in 4 percent of the population also predisposes to respiratory and perhaps liver disease.

Adolescent↗
PubMed1975

The amino acid sequence of the alpha chain of the major haemoglobin of the rat (Rattus norvegicus).

1. A partial amino acid sequence of the alpha chain from the rat (Wistar, Rattus norvegicus) major haemoglobin is reported. The soluble tryptic peptides prepared from aminoethylated alpha-globin were separated by peptide 'mapping'. Sequencing of the tryptic peptides was carried out by the dansyl-Edman method and by the overlapping of smaller peptide fragments derived from secondary enzymic digestion. The insoluble 'core' peptides were further digested with chymotrypsin, thermolysin and pepsin to give smaller soluble peptides for sequencing. The tryptic peptides were ordered on the basis of their homology with the corresponding peptides of human alpha chain. 2. The proposed sequence is compared with that obtained by using an automated sequencer [Garrick et al. (1975) Biochem. J. 149, 245-258]. The differences in sequence resulting from the two methods are discussed. 3. It is suggested that the externally situated cysteine (residue 13) is responsible for the observed inhibition of crystallization of rat haemoglobin at alkaline pH. 4. Detailed evidence for the sequence has been deposited as Supplementary Publication SUP 50047 (9 pages) at the British Library (Linding Division), Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from which copies can be obtained on the terms given in Biochem. J. (1975) 145, 5.

Amino Acid Sequence↗
PubMed1975

The estimation of red cell superoxide dismutase activity.

A method is described for the estimation of red cell superoxide dismutase (erythrocuprein) and a normal range of activity established. It is likely that this enzyme is essential to the red cell for the detoxification of superoxide radicals, and plays a protective role similar to that of the glutathione-glutathione peroxidase system. It is suggested that superoxide dismutase deficiency may be an unrecognized cause of Heinz body hemolytic anemia. The separation of superoxide dismutase from hemoglobin by polyacrylamide gel electrophoresis is also described. Normal superoxide dismutase activity was measured in one case of Wilson's disease.

Adolescent↗