Welcome...

...To the Silvaggi group, located in the Department of Chemistry and Biochemistry at the University of Wisconsin-Milwaukee. The primary focus of this laboratory is the relationship between enzyme structure and function. In other words, how can enzymes with no apparent structural similarity catalyze exactly the same chemical reactions? Or, for that matter, how can two seemingly identical enzymes catalyze very different reactions? These structure-function relationships are important for engineering enzymes to perform specific tasks, or when trying to determine the evolutionary relationships between enzymes, for example. We use X-ray crystallography, steady and transient-state enzyme kinetics, site directed mutagenesis, and other biophysical techniques like isothermal titration calorimetry (ITC) and small-angle X-ray scattering (SAXS). Please scroll down to read about current research highlights, undergraduate research, and the PX Lab Experience.

​ RESEARCH HIGHLIGHT:

The ADC Superfamily Project...

The acetoacetate decarboxylase-like superfamily (ADCSF) is a new and largely unexplored group of enzymes. The prototypical family member, acetoacetate decarboxylase (ADC), catalyzes the cleavage of acetoacetate to give acetone and CO2. The structure of ADC is dominated by a large, discontinuous anti-parallel beta-sheet, which has a compound fold to give two orthogonal "barrels." The large barrel contains the funnel-shaped active site, while the smaller barrel, which has no real interior cavity, forms a platform for dimerization. Taking advantage of the enormous amount of genome sequence data available in public databases, we have identified proteins in most bacterial genomes with significant identity to ADC, especially in the conservation of key active site residues. The SCOP database recognizes this group of proteins as the ADC-like superfamily (ADCSF). We have cloned an expressed a number of family members and shown that none of them possess acetoacetate decarboxylase activity. The contexts of these genes also differ from that of the true ADC genes. Our hypothesis, therefore, is that the ADCSF likely contains enzymes with different catalytic functions and/or substrate specificities. This superfamily provides a unique opportunity to learn about enzyme structure and function, as well as protein engineering of useful biocatalysts.

Read more about on-going research projects here.

​ Undergraduate Research

We take undergraduate research very seriously in this lab. In addition to gaining valuable research experience, undergraduates have made a number of important contributions to our work. So far, every publication coming out of this lab has at least one undergraduate as an author. Students should expect to work an average of 10 hours per week, and to gain experience with every phase of modern structural biology research. This includes cloning/subcloning genes, expression of protein in E. coli, purification by Fast Protein Liquid Chromatography (FPLC), protein crystallization, and X-ray diffraction.  We do work with undergraduates at all skill levels: people have to get lab experience somehow. However, it is true that students with at least rudimentary laboratory skills (pipeting, calculating and measuring reagents and assembling solutions, etc) will derive more benefit from the experience. For this reason, preference is given to students who have completed Chem 603 or other significant laboratory experience. Whether you need to complete research credits for graduation, or are interested in pursuing a career in the biomedical sciences, we encourage you to stop by the lab to talk.