Scaffolding sites

For several years, hydroxyapatite/gelatin bionanocomposite using biomimetic coprecipitation has been pursued as a biological bone substitute because of its biocompatibility, biodegradability and its usage as a scaffold site for regeneration of new bones [221-226]. 

We have considered here possible effects of the protein micro-environment in modulating the properties of photosynthetic chromophores in vivo. Clearly, a combination of axial ligation, hydrogen bonding and nearby residues can define a structural scaffolding that determines the conformations of the molecules and the orientations of their substituents that, in turn, control their photophysical and photochemical characteristics. Note also that if the protein micro-environment does indeed define this scaffolding, site-directed mutations may alter the protein pocket and indirectly affect the conformations and hence the properties of the chromophores. 

The a/p-barrel structure is one of the largest and most regular of all domain structures, comprising about 250 amino acids. It has so far been found in more than 20 different proteins, with completely different amino acid sequences and different functions. They are all enzymes that are modeled on this common scaffold of eight parallel p strands surrounded by eight a helices. They all have their active sites in very similar positions, at the bottom of a funnel-shaped pocket created by the loops that connect the carboxy end of the p strands with the amino end of the a helices. The specific enzymatic activity is, in each case, determined by the lengths and amino acid sequences of these loop regions which do not contribute to the stability of the fold. 

His 57 and Ser 195 are within loop 3-4 of domains 1 and 2, respectively. The third residue in the catalytic triad. Asp 102, is within loop 5-6 of domain 1. The rest of the active site is formed by two loop regions (3-4 and 5-6) of domain 2. As in so many other protein structures described previously, the barrels apparently provide a stable scaffold to position a few loop regions that constitute the essential features of the active site. 

For example, in considering workers in contaminated areas of the site who work on scaffolds, the OSHA Scaffolding Standards are more protective for safety hazards resulting from working on scaffolds. HAZWOPER is more protective for health hazards resulting from the contamination. The applicable provisions of both standards would apply to the work. 

No professional mechanical engineer was on the site at the time. The workers designed and installed the pipe by judgment from experience and got the plant on line in a few days. Flowcver, they did not allow sufficiently for the stress on a 20 inch pipe at 150 psi pressure, or the weakening of the metal from operation at 150° C (302 "F). It was designed on a chalkboard in the workshop and installed with jerry-rigged scaffolding... 

Another commercially available imidazole scaffold upon which a number of other functionalized cations have been constructed is l-(3-aminopropyl)imidazole. The appended amino group in this material is a versatile reactive site that lends itself to conversion into a variety of derivative functionalities (Scheme 2.3-2). 

AKAPs are a diverse family of about 75 scaffolding proteins. They are defined by the presence of a structurally conserved protein kinase A (PKA)-binding domain. AKAPs tether PKA and other signalling proteins to cellular compartments and thereby limit and integrate cellular signalling processes at specific sites. This compartmentalization of signalling by AKAPs contributes to the specificity of a cellular response to a given external stimulus (e.g. a particular hormone or neurotransmitter). 

Scaffolding. Because 14-3-3s can bind potentially bind more than one phosphoprotein at once due the presence of two phosphopeptide-binding sites in a... 

Setton and Chilkoti applied ELPs as a three-dimensional matrix to entrap chondrocytes. In their study, ELP[VsG3A2-90] with a transition temperature of 35°C at 50 mg/mL in PBS was used. This biopolymer can be used to generate a suspension with cells, which upon injection into a defect site will form a scaffold. They showed that in vitro the resulting ELP gel supported the viability of chondrocytes and the synthesis and accumulation of cartilage-specific extracellular matrix material. This suggested that ELPs indeed could be used for in situ formation... 

Recent interest has focused on acidic phosphoproteins, such as bone sialoprotein, acting as sites of nucleation. These proteins contain motifs (eg, poly-Asp and poly-Glu stretches) that bind calcium and may provide an initial scaffold for mineralization. Some macromolecules, such as certain proteoglycans and glycoproteins, can also act as inhibitors of nucleation. 

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