True lipases attach triacylglycerols and act at an oil-water interface; they constitute a ubiquitous group of enzymes catalysing a wide variety of reactions, many with industrial potential. But so far the three-dimensional structure has not been reported for any lipase. Here we report the X-ray structure of the Mucor miehei triglyceride lipase and describe the atomic model obtained at 3.1 A resolution and refined to 1.9 A resolution. It reveals a Ser..His..Asp trypsin-like catalytic triad with an active serine buried under a short helical fragment of a long surface loop.
Neural networks provide a basis for semiempirical studies of pattern matching between the primary and secondary structures of proteins. Networks of the perceptron class have been trained to classify the amino-acid residues into two categories for each of three types of secondary feature: or-helix or not, ]/-sheet or not, and random coil or not. The explicit prediction for the helices in rhodopsin is compared with both electron microscopy results and those of the Chou-Fasman method. A new measure of homology between proteins is provided by the network approach, which thereby leads to quantification of the differences between the primary structures of proteins.
We have developed a program, HookSpace, which provides a simplistic approach to assessing the diversity of molecular databases. The spatial relationship between pairs of intramolecular functional groups can be analysed in a variety of ways to provide both qualitative and quantitative measures of diversity. Results are described and contrasted for two commercially available databases and a combinatorial library of benzodiazepam derivatives. HookSpace highlights the main differences in molecular content of these data sets.
A protein reacting with a monoclonal antibody against human placental diamine oxidase was purified from the specific granules of human neutrofil granulocytes using affinity chromatography on aminohexyldivinylsulfonyl-agarose. The protein had an M, determined by SDS/PAGE, corresponding to diamine oxidase, but had other properties which indicated that it might be a different protein. A combination of protein chemical techniques, including N-terminal sequencing, identified the protein as lactoferrin, an iron-containing protein with an M, of approximately 80000, a high isoelectric point and ferroxidase activity. Purified commercial lactoferrin was shown to bind to aminohexyl-divinylsulfonyl-agarose, and to be eluted in a heterogenous way from the matrix by amines and salt. Alignment of the sequences of diamine oxidase and lactofenin showed that they are similar, indicating a common ancestry for these two different classes of metallo-oxidases.
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