Structural studies on the organization of proteins in mitochondrial membranes using proteolytic enzymes

✍ Scribed by Pasquali, Petronio ;Landi, Laura ;Masotti, Lanfranco ;Lenaz, Giorgio

• Publisher: Wiley (John Wiley & Sons)
• Year: 1973
• Tongue: English
• Weight: 726 KB
• Volume: 1
• Category: Article
• ISSN: 0091-7419
• DOI: 10.1002/jss.400010305

✦ Synopsis

Abstract

Proteolytic enzymes, pronase and trypsin, digest protein in ETP and in SU‐particles (devoid of the soluble ATPase) at similar rates and to the same extents for intact and lipid‐depleted membranes, showing that lipids do not constitute a barrier to the action of the proteases. The rates and extents of hydrolysis are slightly depressed when membranes are reconstituted from lipid‐depleted particles and phospholipids. The hydrolysis rates for the various particles are not greatly enhanced by detergent solubilization nor by other denaturing treatments, indicating that the rates measured in absence of treatments are maximal under the conditions used. The circular dichroism spectra of pronase treated ETP are noticeably altered showing modification of the original conformation. Moreover, enzymic activities of mitochondria and submitochondrial particles are progressively affected by proteases according to their localization at, or near to, a given surface of the membrane. The matrix enzyme, malate dehydrogenase, is not apparently released from mitochondria during the initial incubation period. The results are tentatively discussed in terms of organization of lipids and proteins in the mitochondrial membrane.