[show abstract][hide abstract] ABSTRACT: Lipases are secreted into the culture medium by many bacteria and fungi. They catalyse not only the hydrolysis but also the synthesis of long-chain acylglycerols. Important uses in biotechnology include their addition to detergents, the manufacture of food ingredients, pitch control in the pulp and paper industry, and biocatalysis of stereoselective transformations. This makes them the most widely used class of enzymes in organic chemistry. Immobilization in hydrophobic sol-gel matrices and in vitro evolution are promising novel approaches to increasing the stability or enantioselectivity, respectively, of lipases.
Trends in Biotechnology 10/1998; 16(9):396-403. · 9.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: The crystal and molecular structure of a triacylglyceride lipase (EC 220.127.116.11) from the fungus Rhizomucor miehei was analyzed using X-ray single crystal diffraction data to 1.9 A resolution. The structure was refined to an R-factor of 0.169 for all available data. The details of the molecular architecture and the crystal structure of the enzyme are described. A single polypeptide chain of 269 residues is folded into a rather unusual singly wound beta-sheet domain with predominantly parallel strands, connected by a variety of hairpins, loops and helical segments. All the loops are right-handed, creating an uncommon situation in which the central sheet is asymmetric in that all the connecting fragments are located on one side of the sheet. A single N-terminal alpha-helix provides the support for the other, distal, side of the sheet. Three disulfide bonds (residues 29-268, 40-43, 235-244) stabilize the molecule. There are four cis peptide bonds, all of which precede proline residues. In all, 230 ordered water molecules have been identified; 12 of them have a distinct internal character. The catalytic center of the enzyme is made up of a constellation of three residues (His257, Asp203 and Ser144) similar in structure and function to the analogous (but not homologous) triad found in both of the known families of serine proteinases. The fourth residue in this system equivalent to Thr/Ser in proteinases), hydrogen bonded to Asp, is Tyr260. The catalytic site is concealed under a short amphipatic helix (residues 85 to 91), which acts as "lid", opening the active site when the enzyme is adsorbed at the oil-water interface. In the native enzyme the "lid" is held in place by hydrophobic interactions.
Journal of Molecular Biology 11/1992; 227(3):818-39. · 3.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: SOLVE and RESOLVE have shown that it is possible to automate a significant part of the macromolecular X-ray structure determination process. The key elements of seamless and compatible subprograms, scoring algorithms, and error-tolerant software systems have been important in implementing these programs. The principles used in SOLVE and RESOLVE can be applied to other aspects of structure determination as well, suggesting that full automation of the entire structure determination process from scaling diffraction data to a refined model will be possible in the near future.
Methods in Enzymology 02/2003; 374:22-37. · 2.00 Impact Factor
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