Fructose diphosphatase from rabbit liver. 3. Nature of the groups reactive with dinitrofluorobenzene.

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Fructose diphosphatase from rabbit liver: V. Subunit structure of the purified enzyme

Abstract Fructose 1,6-diphosphatase purified from rabbit liver has a molecular weight of about 127,000. The enzyme is readily dissociated into two subunits by exposure to pH 2.0. Partial reconstitution of the native protein structure and recovery of enzyme activity is obtained by dilution of the dissociated enzyme at neutral pH. Preliminary analyses of the carboxy- and amino-terminal amino acids confirms the existence of two polypeptide chains and suggests that these are not identical

Hemoglobin A1C separation by isoelectric focusing

A modified type of isolectric focusing has been applied successfully to the separation of hemoglobin A1C (HbA1C) from HbA in normal and diabetic cell lysates. It consists of transforming a linear pH gradient into a nonlinear one, by the addition of an amphoteric substance ("separator" or "pH gradient modifier") with an isoelectric point (pI) close to the pI's of the two hemoglobins. Among the "modifiers" tested, histidine, proline, threonine, beta-alanine, 6-amino caproic acid, and 5-amino valeric acid are not useful in the hemoglobin pI range (pH 6.9--7.0). The dipeptide histidyl-glycine (pI = 6.8; pI-pK1 = 1) is very efficient in flattening the pH gradient, in the hemoglobin region. even when added in low concentrations (10--100 mM), thus affording full resolution of the two hemoglobin species

Fructose diphosphatase from rabbit liver. 3. Nature of the groups reactive with dinitrofluorobenzene.

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