Kidney and adrenal mitochondria contain two forms of NADPH-adrenodoxin reductase-dependent iron-sulfur proteins. Isolation of the two porcine renal ferredoxins.

W J Driscoll,J L Omdahl

doi:10.1016/s0021-9258(17)35633-8

Abstract

Two NADPH-adrenodoxin reductase-dependent iron-sulfur proteins were detected in both porcine kidney and bovine adrenal mitochondria by using high resolution polyacrylamide electrophoresis. Adrenodoxin (Mr = 12,000) constituted the major ferredoxin activity in adrenal mitochondria and a similarly sized protein (Mr = 11,500) was isolated as the major renal ferredoxin activity. A second, higher molecular weight ferredoxin was observed in both adrenal (Mr = 13,300) and kidney (Mr = 13,000) mitochondria. The two renal ferredoxins were isolated by the use of ion exchange, gel exclusion, and preparative electrophoretic techniques. An absorption spectrum typical of [2Fe-2S] ferredoxins was obtained for each protein; however, the larger renal molecule had an unusually high 276 nm absorbance. Immunologic studies revealed a significant degree of antigenic commonality between the two renal proteins as well as specific cross-reactivity of adrenodoxin with antiserum raised against the renal proteins. A possible precursor-product relationship between the paired renal and adrenal ferredoxins is discussed.

Highlights

Nificant degree of antigenic commonality between the This endeavor resulted in thediscovery of two ferredoxins two renal proteinsas well as specific cross-reactivity in pig kidney mitochondria
The major pig kidney ferredoxin was very similar to formerly isolated bovine and avian kidney ferredoxins (9, 10)
The previouslyundetected second ferredoxin protein was 1500 Da larger and had a greater number of acidic and aromatic amino acids. It was shown from a competition ELISA that thetwo ferredoxins have shared antigenic determinants

Summary

ISOLATION OF THE TWOPORCINE RENAL FERREDOXINS*

Two NADPH-adrenodoxin reductase-dependent proteins to which adrenodoxin belongs, i.e. the ferredoxins, iron-sulfur proteinws ere detected in both porciknied- contains molecules which have general similarities in strucney and bovine adrenal mitochondria by using high ture and function,yet each appears to be species- and tissueresolutionpolyacrylamideelectrophoresisA. Adrenodoxin’ is one of the most thoroughly characterized iron-sulfur proteins in vertebratesystems It functions at the inner adrenal mitochondrial membrane to transfer electrons from NADPH-adrenodoxin reductase to cytochromes P-450,, or P-45Ol1,2 (2-4). Adrenodoxin hasa molecular mass of approximately 12,000 Da and its [2Fe-%] chromophore imparts a reddish brown color to the protein (5-8) It has a unique optical spectrum with a low 276 nm absorbance and visible maxima a t 414 nmand 454 nm (7). In accordance with the recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature (l), the term renal ferredoxin will denote the iron-sulfur proteins from kidney mitochondria described in thiscommunication

MATERIALS ANDMETHODS

RESULTS

DISCUSSION