Leif Norskov

Bio: Leif Norskov is an academic researcher from Novo Nordisk. The author has contributed to research in topics: Catalytic triad & Affinity chromatography. The author has an hindex of 4, co-authored 4 publications receiving 1192 citations.

A serine protease triad forms the catalytic centre of a triacylglycerol lipase.

Abstract: 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.

Development of an optimized refolding process for recombinant Ala–Glu–IGF-1

Abstract: Denatured and reduced N-terminal extended insulin-like growth factor-1 (AE-IGF-1) was purified from Escherichia coli extracts and subjected to in vitro folding. The renaturation process was shown to be a function of the redox potential of the solution. Folding by different methods had no significant effect on the renaturation. A maximal yield of 60% (w/w) was obtained. The folded AE-IGF-1 was enzymatically converted to IGF-1. The major by-product (20% w/w) was identified as scrambled IGF-1. Enzymatic digestion at alkaline and acidic pH suggested two possible disulphide bond arrangements; (i) Cys6-Cys47, Cys18-Cys61, Cys48-Cys52; or (ii) Cys6-Cys52, Cys18-Cys61, Cys47 and Cys48 being in their reduced forms. Energy minimization and molecular modelling suggested that the scrambled IGF-1, having reduced cysteines at positions 47 and 48, was the energetically most stable conformation of the two.

Characterising the geometric diversity of functional groups in chemical databases

Abstract: 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.

Lactoferrin: similarity to diamine oxidase and purification by aminohexyl affinity chromatography.

Abstract: 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 aminohexyl-divinylsulfonyl-agarose. The protein had an M(r) 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(r) of approximately 800000, 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 lactoferrin showed that they are similar, indicating a common ancestry for these two different classes of metallo-oxidases.

Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein

Abstract: The three-dimensional structure of acetylcholinesterase from Torpedo californica electric organ has been determined by x-ray analysis to 2.8 angstrom resolution. The form crystallized is the glycolipid-anchored homodimer that was purified subsequent to solubilization with a bacterial phosphatidylinositol-specific phospholipase C. The enzyme monomer is an alpha/beta protein that contains 537 amino acids. It consists of a 12-stranded mixed beta sheet surrounded by 14 alpha helices and bears a striking resemblance to several hydrolase structures including dienelactone hydrolase, serine carboxypeptidase-II, three neutral lipases, and haloalkane dehalogenase. The active site is unusual because it contains Glu, not Asp, in the Ser-His-acid catalytic triad and because the relation of the triad to the rest of the protein approximates a mirror image of that seen in the serine proteases. Furthermore, the active site lies near the bottom of a deep and narrow gorge that reaches halfway into the protein. Modeling of acetylcholine binding to the enzyme suggests that the quaternary ammonium ion is bound not to a negatively charged "anionic" site, but rather to some of the 14 aromatic residues that line the gorge.

Metabolic Engineering of Poly(3-Hydroxyalkanoates): From DNA to Plastic

Abstract: Poly(3-hydroxyalkanoates) (PHAs) are a class of microbially produced polyesters that have potential applications as conventional plastics, specifically thermoplastic elastomers. A wealth of biological diversity in PHA formation exists, with at least 100 different PHA constituents and at least five different dedicated PHA biosynthetic pathways. This diversity, in combination with classical microbial physiology and modern molecular biology, has now opened up this area for genetic and metabolic engineering to develop optimal PHA-producing organisms. Commercial processes for PHA production were initially developed by W. R. Grace in the 1960s and later developed by Imperial Chemical Industries, Ltd., in the United Kingdom in the 1970s and 1980s. Since the early 1990s, Metabolix Inc. and Monsanto have been the driving forces behind the commercial exploitation of PHA polymers in the United States. The gram-negative bacterium Ralstonia eutropha, formerly known as Alcaligenes eutrophus, has generally been used as the production organism of choice, and intracellular accumulation of PHA of over 90% of the cell dry weight have been reported. The advent of molecular biological techniques and a developing environmental awareness initiated a renewed scientific interest in PHAs, and the biosynthetic machinery for PHA metabolism has been studied in great detail over the last two decades. Because the structure and monomeric composition of PHAs determine the applications for each type of polymer, a variety of polymers have been synthesized by cofeeding of various substrates or by metabolic engineering of the production organism. Classical microbiology and modern molecular bacterial physiology have been brought together to decipher the intricacies of PHA metabolism both for production purposes and for the unraveling of the natural role of PHAs. This review provides an overview of the different PHA biosynthetic systems and their genetic background, followed by a detailed summation of how this natural diversity is being used to develop commercially attractive, recombinant processes for the large-scale production of PHAs.