A rotenone-insensitive NADH dehydrogenase has been isolated from the mitochondria of the procyclic form of African parasite, Trypanosoma brucei. The active form of the purified enzyme appears to be a dimer consisting of two 33-kDa subunits with noncovalently bound FMN as a cofactor. Hypotonic treatment of intact mitochondria revealed that the NADH dehydrogenase is located in the inner membrane/matrix fraction facing the matrix. The treatment of mitochondria with increasing concentrations of digitonin suggested that the NADH dehydrogenase is loosely bound to the inner mitochondrial membrane. The NADH:ubiquinone reductase activity is insensitive to rotenone, flavone, or dicumarol; however, it was inhibited by diphenyl iodonium in a time- and concentration-dependent manner. Maximum inhibition by diphenyl iodonium required preincubation with NADH to reduce the flavin. More complete inhibition was obtained with the more hydrophobic electron acceptors, such as Q(1) or Q(2), as compared to the more hydrophilic ones, such as Q(0) or dichloroindophenol. Kinetic analysis of the enzyme indicated that the enzyme followed a ping-pong mechanism. The enzyme conducts a one-electron transfer and can reduce molecular oxygen forming superoxide radical.

No abstract

No abstract

Rat liver and kidney mitochondria labeled in vivo with radioactive leucine or valine were fractionated to provide a number of fractions that are reasonably well-recognized biochemical entities. The specific activities of the proteins of these fractions were compared to the specific activity of the unfractionated mitochondrial protein at times varying from 2 min to 8 hr after injection of the labeled amino acid. At short times the specific activities of the water-soluble proteins and the fraction containing cytochrome c were sig-

The Association of American Medical Colleges' Council of Academic Societies (CAS) has a long-standing interest in scholarship as it relates to research, education, and service, the traditional definition of the activities of medical school. The work of Ernest Boyer and Charles Glassick is highly respected for redefining scholarship and conceiving how scholarship as thus defined can be assessed. Because their ideas have been applied in other areas of the academy but not widely in medical faculties, the CAS Task Force on Scholarship collected a special set of papers on Boyer's four areas of scholarship as applied to medical school, including case studies and the perspective from the university. The four areas of scholarship defined by Boyer and Glassick are the scholarship of discovery, the scholarship of integration, the scholarship of application, and the scholarship of teaching. The scholarship of discovery-research-has for decades been the primary focus for promotion and tenure for medical school faculty, even though the faculty also had major and critical activities in the other areas of scholarship. The CAS hopes that the ideas put forth in this special theme issue will produce a continuing dialogue as faculty and administrators at medical schools reflect on the value of these different forms of scholarship, their application by medical school faculty, and their contributions to the individual missions of each medical school and teaching hospital. In addition, these articles will stimulate continuing discussions that will definite equitable methods for the continued assessment of the scholarly accomplishments of medical school faculty.