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A new hernoglobin variant, designated hemoglobin-St Luke's, was detected by routine starch-gel electrophoresis in four members of a Maltese family. The carriers of this abnormality are clinically and hematologically normal. Structural analyses showed the replacement of prolyl residue in position 95 (G2) of the alpha chain by an arginyl residue. The relative amount of hemoglobin-St Luke's present in the red cell hemolysates of its carrier is approximately loo/,, compared to about 2301, for hemoglobin-G Georgia and 15Oj, for hemoglobin-Rampa (the other two variant,s in which prolyl residue a95 (G2) is replaced). Sedimentation velocity studies of hemoglobin-St Luke's in NaCl solutions of increasing concentration up to 2 M indicak &hat the oxy derivative is extensively dissociated into dimers in 0.1 M NaCl a t neutral pH; whereas under the same conditions, the deoxygenated molecule retains a tetrameric structure. In the deoxy state, appreciable tetramer formation occurs even in 2 M NaCI. In addition, association-dissociation in oxyor cyanferrihemoglobin St Luke's is both pH and temperature dependent.Hemoglobins G Georgia and Rainpa are variants in which the proIyl residue in position 95 of the cx chain is replaced by a leucyl and a seryl residue, respectively [I, 2 ) . The liganded derivatives of these abnormal hemoglobins are extensively dissociated into dimers in NaCl solutions of low molarity and a t neutral pH [3]. I n contrast, the deoxygenated derivatives of the two variants are tetramers under the same conditions. The substitution of the prolyl residue occurs a t a site which involves one of the critical contacts ; these contacts are broken when hemoglobin tetramers dissociate into dimers [41. The introduction of either a leucyl residue or a seryl residue in position a95 (G2) ruptures the contacts normally present between Pro-ag5 (G2) and Trp-/337 (C3) in oxygenated hemoglobin [4], and causes an extensive disruption of the al-& contact, probably because the contact becomes accessible to water 131. The greatly increased degree of dimer formation of the two variants is associated with an increased affinity for oxygen and a decrease in heme-heme interaction [3] ; carriers of these abnormalities appear normal.Abbreviation. Hb, hemoglobin.We recently observed an additional variant in which the prolyl residue in position a95 is substituted by an arginyl residue. The variant, t-ermed HbSt Luke's, was present in four members of a Maltese family. This paper describes results of structural analyses and data from sedimentation velocity analyses of the oxy (or cyanferri) and deoxy forms of Hb-St Luke's as a function of salt concentration, pH, and temperature. Results of a few oxygen equilibrium experiments are also included. MATERIALS AND METHODSBlood samples from members of family M were collected with EDTA as anticoagulant. Hematological studies were made by standard methods [5]. Parts of the samples were mailed by air from Malta to Augusta (Georgia, U.S.A.). Hemolysates were prepared by mixing 1 vol. washed packed cel...

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The compound dichloro( 3,B-diamino-1,2,4-dithiazolium) copper(1) has been prepared and its crystal structure determined as a spiraling Cu-C1-Cu chain of approximately tetrahedral CuI bound to three C1 atoms and a ring nitrogen. SYSTEMS containing the S-S linkage and their interactions with metal ions are of considerable interest because of their close relationship to the interaction of metal ions with cystine in biological systems.1 We have generated this linkage as part of a reaction of dithiobiuret with C u n chloride. This reaction gave a positively charged ring system, (S2C2N3HJ4 and CuI is bound to this ring system via a ring nitrogen; this binding has not been observed previously.This reaction between a 95% ethanol solution of CuC1,--2H20 and an ether solution of dithiobiuret (Hdtb, S2C,N,H,) gives three crystalline products : (1) olive green (the material reported here), (2) yellow (under investigation), and(3) a blue material, the eventual end product in air, most likely CuS0,.5H20.