:Contact number

In chemistry, a contact number (CN) is a simple solvent exposure measure that measures residue burial in proteins.{{cite book

|title= Algorithms in Bioinformatics: 8th International Workshop, WABI 2008, Karlsruhe, Germany, September 15–19, 2008, Proceedings Volume 5251 of Lecture notes in bioinformatics|authorlink1=Keith A. Crandall

|author1=Keith A. Crandall |author2=Jens Lagergren

|year= 2008

|publisher= Springer

|location=

|isbn= 978-3-540-87360-0

|page= 382

|url= https://books.google.com/books?id=SYADy4_LYYMC&pg=PA382}} The definition of CN varies between authors, but is generally defined as the number of either C$\backslash beta$ or C$\backslash alpha$ atoms within a sphere around the C$\backslash beta$ or C$\backslash alpha$ atom of the residue. The radius of the sphere is typically chosen to be between 8 and 14Å.