Proteins also

The VFe protein also has the equivalent of P-cluster pairs which have similar properties to those found in the MoFe protein (159). No information is available on whether P-cluster pairs exist in the FeFe protein, but because of the relatively high sequence identity and the similar genetic basis of its biosynthesis, the occurrence seems highly likely. The catalytic role assigned to the P-cluster pair involves accepting electrons from the Fe protein for storage and future deUvery to the substrate via the FeMo-cofactor centers. As of this writing (ca early 1995), this role has yet to be proved. 

To put the errors in comparative models into perspective, we list the differences among strucmres of the same protein that have been detennined experimentally (Fig. 9). The 1 A accuracy of main chain atom positions corresponds to X-ray structures defined at a low resolution of about 2.5 A and with an / -factor of about 25% [192], as well as to medium resolution NMR structures determined from 10 interproton distance restraints per residue [193]. Similarly, differences between the highly refined X-ray and NMR structures of the same protein also tend to be about 1 A [193]. Changes in the environment... 

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. 

Motor proteins, also known as molecular motors, use chemical energy (ATP) to orchestrate all these movements, transforming ATP energy into the mechanical energy of motion. In all cases, ATP hydrolysis is presumed to drive and... 

The photoprotein is non-fluorescent. The absorption spectrum of purified photoprotein shows a very small peak at 410 nm, in addition to the protein peak at 280 nm (Fig. 10.2.5). The peak height at 410 nm appears to be proportional to the luminescence activity of the protein. The protein also shows extremely weak absorption peaks at about 497, 550 and 587nm (not shown). These absorption peaks, except the 280 nm peak, might be due to the presence of a chromophore that is functional in the light emission. 

Two mechanisms are operating alone or in concert to minimize the antibiotic concentration at the intracellular target site Downregulation of the expression of the pore proteins, also called porins, and upregulation of one or a set of several unspecific efflux pumps. However, the impact of these mechanisms on the resistance is low, since due to the essential function of porins for uptake of nutrients their reduction is limited and to avoid disturbances of membrane integrity due to extensive oveiproduction of mdr efflux pumps these are subjected a strict regulation. 

These cytosolic proteins contain five EF-hand domains and are able to translocate to the plasma membrane upon calcium binding [5]. In addition to the EF-hand domains, these proteins also have a hydrophobic glycine/proline-rich domain, important for their translocation to the membrane. To date five members of this... 

NFAT2 plays a key role in the development of the embryo s heart. In the precursor cells, there is a temporal and spatial specific expression of NFAT2, which directs the formation of the valves and the septum in the heart. In the adult heart, NFAT proteins also cooperate with transcription factors of the GATA and MEF2 families to regulate cardiac muscle hypertrophic responses. 

Both tumor necrosis factor receptors (TNFR) are type I transmembrane proteins, also belonging to a large family of proteins, the TNFR superfamily... 

Most medical students look askance at thermobiology. We think this is a mistake hence, we have included a section dealing with this subject. This brings us to the chapter on the heat shock response which at the very outset makes clear that many stressors besides heat are known to result in heat shock gene expression. Many of the heat shock proteins occur in unstressed cells and some of them behave as chaperones. These proteins also reach high levels in a wide range of diseases... 

In nature, there are 20 amino acids available for incorporation into the protein chain. They are arranged in a specific and characteristic sequence along the molecule. This sequence is generally referred to as the primary structure of the protein. Also part of the primary structure is the relative molar mass of the macromolecule. 

Resonance Raman studies on the putative prismane protein would provide other important information. In the frequency region of 200-430 cm the putative prismane protein showed bands that at first sight seemed to be typical for Fe-S clusters, but at a closer look appeared to be broader than those observed in basic Fe-S proteins. Also, the resonance frequencies were slightly different from known Fe-S clusters, and it was contended that A prismane-type [6Fe-6S] core is clearly an excellent candidate in light of the available analytical and biophysical data [28]. 

---