Reference XPS spectra of amino acids

A Artemenko,T Wågberg,P Štenclová,J Segervald,X Jia,A Shchukarev,A Kromka

doi:10.1088/1757-899x/1050/1/012001

Abstract

In this report we present XPS data for five amino acids (AAs) (tryptophan, methionine, glutamine, glutamic acid, and arginine) with different side chain groups measured in solid state (powder form). The theoretically and experimentally obtained chemical structure of AAs are compared. Here, we analyse and discuss C 1 s, N 1 s, O 1s and S 2p core level binding energies, FWHMs, atomic concentrations of the functional groups in AAs. The experimentally obtained and theoretically calculated ratio of atomic concentrations are compared. The zwitterionic nature of methionine and glutamine in solid state was determined from protonated amino groups in N 1s peak and deprotonated carboxylic groups in the C 1s spectrum. The obtained XPS results for AAs well correspond with previously reported data.

Highlights

Amino acids (AAs) could be considered as one of the smallest biomolecules which are defined as organic compounds with both an amino group and a carboxyl group in one molecule
In this report we present X-ray photoelectron spectroscopy (XPS) data for five amino acids (AAs) with different side chain groups measured in solid state
We present a detailed XPS analysis of five amino acids in the solid state which differ in their structure, namely in side chains

Summary

Introduction

Amino acids (AAs) could be considered as one of the smallest biomolecules which are defined as organic compounds with both an amino group and a carboxyl group in one molecule. The most important is that AAs are the basic building blocks of more complex organic materials such as peptides and proteins which are the objects of numerous investigations in biomaterials science. It is important to have detailed and reliable experimental data for reference AAs (including the position of core level peaks, characterization of functional groups, atomic concentrations, etc.) for further investigation of more complex organic tissues. X-ray photoelectron spectroscopy (XPS) is one of the most powerful methods for the characterization of the surface chemistry of a wide variety of materials. As the depth of analysis in XPS (< 10 nm) is limited by the escape depth of photoelectrons from solid materials it is successfully used as a surface-sensitive method

Methods

Results

Conclusion