Decades of research in opioid analgesia culminated in the discovery of the endogenous opioid peptides (see Analgesics, antipyretics, and antiinflammatory AGENTS Neuroregulators). Early studies of the stmcture—activity relationships of opiate alkaloids (qv) had provided evidence of the stereospecificity and antagonist reversibiUty of opiate action, suggesting that these dmgs acted through specific receptors. However, pioneering attempts to demonstrate specific opiate receptors in the brain met with only marginal success, largely because researchers were limited to high ligand concentrations resulting from the low specific activity of opioid ligands available at that time (1). In 1973, stereospecific opioid binding in rat brain was independendy demonstrated in three separate laboratories (2—4). These demonstrations rehed on comparison of binding by stereoisomers, eg, levorphanol [77-07-6] and its inactive enantiomer, dextrorphan [125-73-5] which differed by four orders of magnitude in their abiUty to bind to opiate receptors. Radioligands having high specific activity (3.7-14.8 X 10 Bq/mmol (10—40 Ci /mmol)) were essential to these studies (see Radioactive tracers).  [c.444]

Alpha helices are sufficiently versatile to produce many very different classes of structures. In membrane-bound proteins, the regions inside the membranes are frequently a helices whose surfaces are covered by hydrophobic side chains suitable for the hydrophobic environment inside the membranes. Membrane-bound proteins are described in Chapter 12. Alpha helices are also frequently used to produce structural and motile proteins with various different properties and functions. These can be typical fibrous proteins such as keratin, which is present in skin, hair, and feathers, or parts of the cellular machinery such as fibrinogen or the muscle proteins myosin and dystrophin. These a-helical proteins will be discussed in Chapter 14.  [c.35]

Dystrophin is located on the cytoplasmic face of the muscle  [c.548]

A comparison of the amino acid sequences of dystrophin, a-actinin, and spectrin. The potential hinge segments in die dystrophin structure are indicated.  [c.548]

When a distribufion of particle sizes which must be collected is present, the aclual size distribution must be converted to a mass distribution by aerodynamic size. Frequently the distribution can be represented or approximated by a log-normal distribution (a straight line on a log-log plot of cumulative mass percent of particles versus diameter) wmich can be characterized by the mass median particle diameter dp5o and the standard statistical deviation of particles from the median [c.1428]

The leucine zipper DNA-binding proteins, described in Chapter 10, are examples of globular proteins that use coiled coils to form both homo- and heterodimers. A variety of fibrous proteins also have heptad repeats in their sequences and use coiled coils to form oligomers, mainly dimers and trimers. Among these are myosin, fibrinogen, actin cross-linking proteins such as spectrin and dystrophin as well as the intermediate filament proteins keratin, vimentin, desmin, and neurofilament proteins.  [c.287]

Koenig, M., and Knnkel, L., 1990. Detailed analysis of die repeat domain of dystrophin reveals four potendal hinge segments that may confer flexibility. of Biological Chemistry 265 4560-4566.  [c.564]

See pages that mention the term Dystrophin : [c.91]    [c.291]    [c.36]    [c.492]    [c.548]    [c.548]    [c.548]    [c.549]    [c.549]    [c.549]    [c.564]    [c.710]   
Introduction to protein structure (1999) -- [ c.36 ]