Crystallized protein

There are indications that the crystal protein is subject to proteolytic enzymes when separated from the sporangium. The crystal protein has also been shown to be degradable by fairly nonspecific proteases such as pepsin and trypsin. 

Its solubility characteristics in aqueous systems are such that retention of toxicity to insects by dissolved crystal protein is always suspect, and loss of activity on dissolution owing to denaturation is often observed. The protein is soluble only in relatively strong aqueous alkali. Thus, it has been variously reported to be soluble in 0.01N- to 0.05N sodium hydroxide (1) and alkali at pH 10.5 in the presence of thioglycollate (35) we have also observed its solubility in alkali at pH 9.5 in the presence of urea and potassium boro hydride. One difference between the characteristic proteins produced by various strains of crystalliferous bacilli is observed in the degree of alka-... 

There has been remarkable progress in techniques for crystallizing proteins. 

Wei, J. Z., Hale, K., Carta, L., Platzer, E., Wong, C., Fang, S. C. and Aroian, R. V. (2003). Bacillus thuringiensis crystal proteins that target nematodes . Proceedings National Academy Science USA, 100(5), 2760-2765... 

As described earlier, there are a number of different ways of crystallizing proteins. By far, the most common approach is the vapor-diffusion method, as mentioned earlier. Approximately, 70% of the crystal structures reported have been crystallized through variations of the vapor-diffusion method. The technique can be carried out in a number of ways the simplest two being the hanging drop method, and the sitting drop ... 

StoU VS, Manohar AV, Gillon W, Mac Farlane EL, Hynes RC, et al. 1998. A thioredoxin fusion protein of VanH, a d-lactate dehydrogenase from Enterococcus Faecium cloning, expression, purification, kinetic analysis, and crystallization. Protein Sci 7 1147-1155. 

Since the X-ray structural analysis of crystallized proteins yields the most direct information on the tertiary structure, many attempts have been made in the last decade to crystallize individual ribosomal proteins. However, it was many years before any progress in this field was made. The N- and C-terminal fragments of the . coU protein L7/L12 have been crystallized, and the crystals diffract to 4 and 2.6 A, respectively (Liljas et ai, 1978). According to the X-ray analysis, the C-terminal fragment (positions 53-120) has a compact, plum-shaped tertiary structure with three a helices and three p sheets (Leijonmarck et ai, 1980). 

DXMS-guided Design of Well Crystallizing Proteins 383... 

Poorly Crystallizing Proteins Contain Substantial Disordered Regions... 

While there exist empirical rules for determining conditions favorable for protein crystallization, protein crystallization remains predominantly a trial-and-error process. 

Liss, M., Petersen, B., Wolf, H. and Prohaska, E. (2002) An aptamer-based quartz crystal protein biosensor, Anal. Chem. 74, 4488 1495. 

Knowing that crystallographers study proteins in the crystalline state, you may be wondering if these molecules are altered when they crystallize, and whether the structure revealed by X rays is pertinent to the molecule s action in solution. Crystallographers worry about this problem also, and with a few proteins, it has been found that crystal structures are in conflict with chemical or spectroscopic evidence about the protein in solution. These cases are rare, however, and the large majority of crystal structures appear to be identical to the solution structure. Because of the slight possibility that crystallization will alter molecular structure, an essential part of any structure determination project is an effort to show that the crystallized protein is not significantly altered. 

Figure 11 Packing coefficients in various states organic crystals, protein cores, inclusion crystals, encapsulated hosts and the liquid state.

Tertiary (3°) Overall 3D structure Protein crystal Protein structure... 

A number of functional studies have shown that the partially ligated species and valency hybrid Hbs exhibit slowly interconverting conformation states. Some of them have properties that are intermediate between those associated with the T- and R-quaternary conformations (Cassoly and Gibson, 1972 Samaja et al., 1987 Sharma, 1989 Berjis et al., 1990). Thus, one needs to be careful in making correlations between a given crystal structure of a specific Hb species and its functional properties. It should be kept in mind that crystallization is a selective procedure, i.e., it selects those proteins with specific structures that are crystallizable under a given set of crystallization conditions. The structures of these crystallized proteins may not be the dominant ones when function is measured under solution conditions different from those used in crystallizing the proteins. 

Determination of Atomic Desolvation Energies from the Structures of Crystallized Proteins. 

Determination of Atomic Solvation Energies from the Structure of Crystallized Proteins. 

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