Abstract
Extremely low lactate dehydrogenase (LD; EC 1.1.1.27) activity in the serum of a 43-year-old man was noted in health examinations. The LD isozyme from the patient showed a characteristic pattern with only two isozyme bands of LD-4 and LD-5 in the serum, erythrocytes, lymhpocytes and saliva. A model experiment of in vitro hybridization indicated that M4 with a very low proportion of H4 gave zymograms similar to those obtained from this patient. Other LD isozymes related to the H-subunit were detected in stimulated lymphocytes (LD-3), and young erythrocytes (LD-1 and LD-2). These results suggest that this case is a new type of H-subunit deficiency in which the produced H-subnit protein is rapidly inactivated in vivo.
