Solubilization of membranes by detergents

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.

Fiber types in mammalian skeletal muscles.

C YTOCHALASINS and phalloidins are two groups of small, naturally occurring organic molecules that bind to actin and alter its polymerization. They have been widely used to study the role of actin in biological processes and as models for actin-binding proteins. Functionally, cytochalasins resemble capping proteins, which block an end of actin filaments, nucleate polymerization, and shorten filaments. No known actin-binding protein stabilizes actin filaments as phalloidin does, but such proteins may have been missed. Cytochalasin and phalloidin have also helped to elucidate fundamental aspects of actin polymerization. This review briefly summarizes older studies and concentrates on recent v~rk on the mechanisms of action of cytochalasin and phalloidin.

/pdf/effects-of-cytochalasin-and-phalloidin-on-actin-1n5utwhpou.pdf

Effects of cytochalasin and phalloidin on actin.

Myosin was isolated from 14 different muscles (mammals, lower vertebrates, and invertebrates) of known maximal speed of shortening. These myosin preparations were homogeneous in the analytical ultracentrifuge or, in a few cases, showed, in addition to the main myosin peak, part of the myosin in aggregated form. Actin- and Ca++-activated ATPase activities of the myosins were generally proportional to the speed of shortening of their respective muscles; i.e. the greater the intrinsic speed, the higher the ATPase activity. This relation was found when the speed of shortening ranged from 0.1 to 24 muscle lengths/sec. The temperature coefficient of the Ca++-activated myosin ATPase was the same as that of the speed of shortening, Q10 about 2. Higher Q10 values were found for the actin-activated myosin ATPase, especially below 10°C. By using myofibrils instead of reconstituted actomyosin, Q10 values close to 2 could be obtained for the Mg++-activated myofibrillar ATPase at ionic strength of 0.014. In another series of experiments, myosin was isolated from 11 different muscles of known isometric twitch contraction time. The ATPase activity of these myosins was inversely proportional to the contraction time of the muscles. These results suggest a role for the ATPase activity of myosin in determining the speed of muscle contraction. In contrast to the ATPase activity of myosin, which varied according to the speed of contraction, the F-actin-binding ability of myosin from various muscles was rather constant.

/pdf/atpase-activity-of-myosin-correlated-with-speed-of-muscle-388ukhy31w.pdf

ATPase Activity of Myosin Correlated with Speed of Muscle Shortening

Relaxing factor and the relaxation of muscle

[The calcium pump of the "relaxing granules" of muscle and its dependence on ATP-splitting].

Interaction of actin with phalloidin: polymerization and stabilization of F-actin.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2871%2980196-5

ATP synthesis by the reverse of the sarcoplasmic calcium pump.

http://www.jbc.org/content/246/15/4759.full.pdf

Wilhelm Hasselbach

Papers

Relaxing factor and the relaxation of muscle

[The calcium pump of the "relaxing granules" of muscle and its dependence on ATP-splitting].

Interaction of actin with phalloidin: polymerization and stabilization of F-actin.

ATP synthesis by the reverse of the sarcoplasmic calcium pump.

Acetyl Phosphate as Substrate for Ca2+ Uptake in Skeletal Muscle Microsomes INHIBITION BY ALKALI IONS