Significance of a new type of human fetal hemoglobin carrying a replacement isoleucine ? threonine at position 75 (E 19) of the ? chain

Ricco, G; Mazza, U; Turi, R. M.; Pich, P. G.; Camaschella, Clara; Saglio, Giuseppe; Bernini, L. F.

doi:10.1007/bf00295821

Cited by 110 publications

(39 citation statements)

References 14 publications

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“…The recent discovery of the Ty-chain by Ricco et al. (3) has added yet another facet to the many ways in which the study of Hb-F has provided data about the genetics ofthis fetal protein. In the Ty-chain, the isoleucyl residue at position 75 of the y-chain is replaced by a threonyl residue.…”

Section: Introductionmentioning

confidence: 99%

Further studies of the frequency and significance of the Tgamma-chain of human fetal hemoglobin.

Schroeder¹,

Huisman²,

Ефремов³

et al. 1979

J. Clin. Invest.

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Section: Introductionmentioning

confidence: 99%

Further studies of the frequency and significance of the Tgamma-chain of human fetal hemoglobin.

Schroeder¹,

Huisman²,

Ефремов³

et al. 1979

J. Clin. Invest.

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“…Moreover, the recent discovery in a large proportion of normal and thalassemic subjects (8) of a variant -y chain having threonine instead of isoleucine (8,9) METHODS CM-Cellulose Chromatography of Globin Chains. Purified a, f, and y globin chains were obtained by CM-cellulose chromatography (10) of acid/acetone-precipitated total globin chains (10).…”

mentioning

confidence: 99%

Human T gamma globin chain is a variant of A gamma chain (A gamma Sardinia).

Saglio

Ricco

Mazza

et al. 1979

Proc. Natl. Acad. Sci. U.S.A.

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Isoelectric focusing, cellulose acetate electrophoresis, and carboxymethylcellulose chromatography in the presence of Nonidet P 40 allow the separation of pure y globin chains into two fractions. Amino acid analysis of their cyanogen bromide fragment 3 ('yCB3) identifies these fractions as the separated C7 (Gly-136) and A7 The -y globin chains of human fetal hemoglobin are a heterogeneous mixture of two major species differing in position 136, which is occupied either by a glycyl residue (G chain) or by an alanyl residue (Ay chain); all normal individuals of different geographic areas or races so far examined have these two chains, a fact suggesting, with other genetic and molecular hybridization evidence, that these chains are the product of at least two nonallelic structural genes (1-5).The Gy and AK chains, differing only by a neutral amino acid residue, have identical charge and size, thus preventing their separation by standard chromatographic and electrophoretic techniques. So far their quantitation could be obtained only by analysis of a specific cyanogen bromide fragment including the variant residue for its glycine and alanine contents. Limits inherent to this method prevent biosynthetic studies using radioactive amino acids and do not allow its application to extensive surveys.In the course of studies on the separation by isoelectric focusing (IEF) of human globin chains, we observed that chromatographically pure y globin chains were split into two bands upon addition of the detergent Nonidet P-40 (NP-40) (6); on the basis of comparison of the relative intensities of the bands and the Gy/Ay ratios in different samples, we suggested that these bands might represent separated Gy and Ay chains, and that this technique could be used for biosynthetic studies (7). By using a chromatographic technique we have now been able to prepare amounts of material corresponding to each band, adequate for demonstrating unambiguously that these two bands are in fact separated Gy and Ay chains.Moreover, the recent discovery in a large proportion of normal and thalassemic subjects (8) of a variant -y chain having threonine instead of isoleucine (8,9) METHODS CM-Cellulose Chromatography of Globin Chains. Purified a, f, and y globin chains were obtained by CM-cellulose chromatography (10) of acid/acetone-precipitated total globin chains (10). For radioactive experiments, the globin chains were labeled by incubating 1 ml of peripheral blood with 100,uCi(1 Ci = 3.7 X 1010 becquerels) of lyophilized L-[4,5-3H]leucine (110 Ci/mmol) and 2 mg of glucose at 37°C for 1 hr. For analytical experiments, a 5-32.5 mM sodium phosphate gradient (pH 6.8) of 300 ml was used; when indicated, 3% (vol/vol) NP-40 was included. For preparative fractionation of GY and Ay chains, 20-50 mg of purified y globin chains was loaded onto a 6 X 2.5 cm column and eluted with an 800-ml 5-19 mM sodium phosphate gradient containing 3% NP-40. Thirtymicroliter aliquots from every second fraction were analyzed by IEF as described below, and fractio...

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“…The globins were submitted to tryptic digestion and to fingerprinting on paper [4] and on thin layer [ll].…”

Section: Methodsmentioning

confidence: 99%

“…A variant of Hb F, Hb F Sardinia (ars$s 75 Ile + Thr) [3] is of unusual high frequency in various populations at birth [4,5]. Very recent results of peptide analysis suggested that the 775 Thr chain is a variant produced by the A7 locus [6,7] and corresponds to a genetic polymorphism.…”

Section: Introductionmentioning

confidence: 99%