Vesicular stomatitis virus was extracted with 60 mM octylglucoside in the absence of salts and in the presence of 0.5 M NaCl. The resulting extracted virus particles were examined by electron microscopy, and the proteins present were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Extraction in the absence of salts yielded subviral structures which we cell "skeletons" as originally suggested by Cartwright et al. (J. Gen. Virol. 7:19-32, 1970). The skeletons contained the viral N, M, and L proteins, but they lacked the glycoprotein (G) entirely. Morphologically, the skeletons resembled intact vesicular stomatitis virus but they were slightly longer and smaller in diameter. Like native vesicular stomatitis virus, skeletons were found to have lateral striations spaced 5.0 to 6.0 nm apart along the length of the structure. In contrast to extraction in the absence of NaCl, extraction of vesicular stomatitis virus with 60 mM octylglucoside in the presence of 0.5 M NaCl yielded highly extended viral nucleocapsids in which N was the predominant protein; no M or G proteins could be detected. These results support the view that the M protein is involved in maintaining the nucleocapsid in the compact form found in native virions.

SUMMARY– Proteolysis and its relationship to tenderness were studied by measuring nonprotein nitrogen (NPN), free amino groups, and shear resistance during post‐mortem aging of bovine muscle. Both NPN and free amino groups increased during post‐mortem aging, indicating some degradation of proteins and/or peptides. However, neither the increase in NPN nor free amino groups was related to post‐mortem tenderization since these quantities increased only after most of the improvement in tenderness had occurred. Much of the increase in NPN or free amino groups may originate from degradation of sarcoplasmic proteins or peptides. It is suggested that weakening or breaks at crucial points in the sarcomere, such as at the junction of the Z‐line with the thin filaments, occur within the first 48‐72 hr post‐mortem and that this weakening or cleavage is responsible for tenderization. Cathepsin D may be responsible for this weakening but most of the available evidence is against proteolysis as the primary cause of post‐mortem tenderization.