Abstract: Engineered sortase variants are shown to have promiscuous activity that allow proteins to be tagged using a diverse array of small, commercially available amines, including bioorthogonal functional groups. This technique can also be carried out in living microbial cells, enabling simple, inexpensive production of chemically functionalized proteins with no additional purification steps. The methods find use in the site specific conjugation of drugs, imaging probes and other chemical moieties to proteins and peptides.

Abstract: A method of producing spectral data corrected for background includes generating spectral data, ascertaining background and subtracting background points to produce the corrected data. To ascertain background the spectral data are masked initially at the spectral peak of interest, and a least squares curve is fitted to the masked data. A runs test is performed to detect whether the number of runs exceeds a selected significance level. If so, the data are further masked and a curve is refitted. These steps are iterated until no further significant number of runs is detected. Similar testing for outliers is then effected with similar masking, a final curve represents the background level.