Protein complexes are dynamic macromolecules that constantly dissociate into, and simultaneously are assembled from, free subunits. Dissociation rate constants, k(off), provide structural and functional information on protein complexes. However, because all existing methods for measuring k(off) require high-quality purification and specific modifications of protein complexes, dissociation kinet...

The use of stable isotopes to solve biogeochemical problems in ecosystem analysis is increasing rapidly because stable isotope data can contribute both source-sink (tracer) and process information: The elements C, N, S, H, and all have more than one isotope, and isotopic compositions of natural materials can be measured with great precision with a mass spectrometer. Isotopic compositions change...

In this work an improved stable isotope labeling protocol for nucleic acids is introduced. The novel building blocks eliminate/minimize homonuclear (13) C and (1) H scalar couplings thus allowing proton relaxation dispersion (RD) experiments to report accurately on the chemical exchange of nucleic acids. Using site-specific (2) H and (13) C labeling, spin topologies are introduced into DNA and ...

and ‘depleted’ to describe both isotopic ratios and the amount of each isotope. This is at times very confusing. Can I please request that when referring to enrichment or depletion of a specific isotope that it is noted which one is being discussed. Further, isotope ratios themselves are not strictly speaking enriched/depleted they are, e.g., higher/lower. A little thing but separating the term...

The currently available results of the isotope effect on the superconducting transition temperature Tc in Fe-based high-temperature superconductors (HTSs) are highly controversial. The values of the Fe isotope effect exponent �Fe for various families of Fe-based HTS were found to be as well positive, as negative, or even be exceedingly larger than the BCS value �BCS�0.5. Here we emphasize that ...

Identification and relative quantification of hundreds to thousands of proteins within complex biological samples have become realistic with the emergence of stable isotope labeling in combination with high throughput mass spectrometry. However, all current chemical approaches target a single amino acid functionality (most often lysine or cysteine) despite the fact that addressing two or more a...

Robust quantification of analytes is a prerequisite for meaningful metabolomics experiments. In non-targeted metabolomics it is still hard to compare measurements across multiple batches or instruments. For targeted analyses isotope dilution mass spectrometry is used to provide a robust normalization reference. Here, we present an approach that allows for the automated semi-quantification of me...

If A is a unital associative algebra and u is invertible in A, one can define an algebra A, called the u-isotope of A, which is equal to A as a vector space but has a new product x ·u y = xuy. This isotope A (u) is again unital and associative but with a shifted identity element u. More generally there are definitions of isotope for several other classes of unital nonassociative algebras, notab...

A new method for the measurement of calcium isotope ratios and total calcium, using a double focusing sector field inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with a shielded torch, is presented. The method was applied for the measurement of the Ca/Ca, Ca/Ca and Ca/Ca ratios and total calcium by isotope dilution in urine samples from two different nutritional exper...

This study investigates dual element isotope fractionation during aerobic biodegradation of 1,2-dichloroethane (1,2-DCA) via oxidative cleavage of a C-H bond (Pseudomonas sp. strain DCA1) versus C-Cl bond cleavage by S(N)2 reaction (Xanthobacter autotrophicus GJ10 and Ancylobacter aquaticus AD20). Compound-specific chlorine isotope analysis of 1,2-DCA was performed for the first time, and isoto...