Preparation and characterization of an enzymatically active immobilized derivative of myosin

The isolation and purification of two anionic endothelial cell growth factors from human brain

Two anionic polypeptides which stimulate the proliferation of human umbilical vein endothelial cells have been isolated and purified to homogeneity from human brain using heparin affinity chromatography. The molecular weights of the polypeptides are 18,500 and 19,300; the isoelectric point for both polypeptides is at pH 5.2. The purified polypeptides differed in their ability to stimulate human endothelial cell growth. The half maximal activities observed for the 18.5 and 19.3 kilodalton polypeptides were at concentrations of 10.0 ng/ml and 0.9 ng/ml respectively.

An in vitro study of the interactions of skeletal muscle M-protein and creatine kinase with myosin and its subfragments

Two proteins reported to be located in the M-band of skeletal muscle are M-protein (Mr 160,000) and creatine kinase (Mr 83,000). We have isolated and purified these proteins from adult chicken pectoralis muscle, and have studied their in vitro interactions with myosin, heavy meromyosin, light meromyosin and subfragment-2 in order to obtain a fuller understanding of the role these proteins play in the M-band of skeletal muscle. Experiments using the techniques of analytical ultracentrifugation, affinity chromatography and electron microscopy were carried out near physiological pH and ionic strength, under which conditions the M-band proteins are known to be firmly bound to the myofibril in situ. The results of our studies indicate that such interactions are either weak or absent in vitro. Discrepancies between our results and those from several other studies are discussed. We conclude that additional components may be required in order to observe interactions in vitro which are similar to those present in the intact myofibril.