A small but very useful feature has been added for our MS user base. When Mass Spectrometrists acquire data the masses may carry a positive charge or a negative charge. They may actually be up two proton masses or down a proton mass. For certain species the masses may be up an electron mass or down an electron mass. Since so many measurements today are made as high resolution monoisotopic masses then the addition or subtraction of an electron mass can certainly have an impact on the results of the search.
Previously we have expected our users to add or subtract the masses of the protons or electrons prior to performing their searches. HOW UNFRIENDLY! So, we’ve introduced the ability to simply declare the appropriate charges during the search. Checkout the screen below…it should be self-explanatory. The search is available under the Advanced tab on the search page and by selecting the “Search by Properties” tab.