MOLECULAR PACKING STUDY OF DIFFERENT CRYSTALFORMS OF T4 LYSOZYME
T4溶菌酶晶体分子堆积的研究

The molecular packing was analyzed with 10 different crystal forms of T4 lysozyme, where there is only one protein molecule in an asymmetric unit. The proportion of non-polar atoms involved in all interface areas in the crystal forms with higher solvent content is larger than that in the crystal forms with lower solvent content; the proportion of polar or charged atoms involved in all interface areas in the crystal forms with higher solvent content is less than that in the crystal forms with lower solvent content. Most crystal forms with higher solvent content contain 2-fold symmetry axes, which are rare in the crystal forms with lower solvent content. Compared to other contacts, contacts between 2-fold axis-related molecules contain less polar interactions. These results imply that the solvent content might be affected by different intermolecular interactions caused by different crystallization environments. In addition, no specific contacts were found in the molecular packing of T4 lysozyme crystals, and this confirms that the crystal packing is essentially non-specific. However, it has been reveaved that some polar or charged residues which have larger accessible surface areas, are of importantce for crystal packing, and these important residues may often present in intermolecular contacts in different crystal forms.