RAPID DESTRUCTION OF NEWLY SYNTHESIZED EXCESS BETA-GLOBIN CHAINS IN HBH DISEASE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 57  (5) , 967-971
Abstract
A subject with HbG Philadelphia-HbH disease exhibited an unusually high .alpha./.beta. synthesis ratio; when peripheral blood was tested in vitro on several occasions, ratios of 0.63-0.89 were obtained after incubations of 30-120 min. HbH amounted to 5-8% of the circulating Hb. Rapid destruction of excess newly synthesized .beta.-globin was demonstrated in kinetic and pulse-chase experiments. After 2 min of incubation the .alpha./.beta. synthesis ratio was 0.48; this figure rose to 0.89 by 30 min. The zero time .alpha./.beta. ratio was estimated to be 0.35. The degradation of .beta.-chains was calculated to proceed at .apprx. 1/2 the rate of .beta.-globin synthesis; this result was confirmed by the loss of 50% of the specific activity in .beta.-chains during 9 min of a chase experiment following a 10-min radioactive pulse. Efficient proteolysis may be responsible, in some blacks, for the low levels of excess .beta.-globin chains in HbH disease as well as for the mildness of the clinical disorder.