Raman and ROA

At HTL Biosolutions, Inc., we offer both consulting and contract research services on protein characterizations, stability testings and formulation development.

ROA stands for Raman Optical Activity and provides structural information about the chiral property of a functional group. Raman spectroscopy has been often used to investigate protein secondary structures and side chain conformations. One of the major advantages of Raman spectroscopy is its versatility to study proteins in virtually all physical states, including solution, solid, colloid and gel states.

Key Benefits of ROA
1.  Comparability study of lot-to-lot variation
2. Analysis of protein tertiary structure
3.  Analysis of side chain conformations, such as Trp, Tyr, S-S etc.

Raman and ROA spectra of monoclonal antibody at pH 3 and 7.


To probe conformational changes in proteins
ROA can be used to detect changes in protein tertiary and secondary structures. Protein side chain conformations including Trp, Tyr and Cys can also be determined by Raman and ROA spectroscopy.

To distinguish different types of protein secondary structures

VCD spectroscopy can be used to detect different types of protein secondary structures including alpha-helix, 3-10 helix, hydrated alpha-helix, parallel and anti-parallel beta-sheets.

To determine protein-protein and protein-ligand interactions

FTIR, VCD, Raman and ROA can be used to probe structural changes in proteins resulted from protein-protein and/or protein-ligand interactions.

Key Benefits of Raman Spectroscopy
1.  Comparability study of lot-to-lot variations
2.  Analysis of protein secondary structures and side chain conformations
3.  Analysis of DNA and RNA conformations
4.  Ananlysis of protein-DNA and protein-RNA interactions
5.  Analysis of virus structures and assembly-disassembly process of viruses

Analysis of solid protein samples
Raman spectroscopy can be used as an effective tool to study structure of proteins in solid states, such as lyophilized protein formulations, spray-dried protein powders, and that of proteins in sustained release formulations such as PLGA microspheres or other solid dosage forms.

Analysis of protein-excipient interactions

Effect of formulation excipients such as sugars, polymers and preservatives on protein structure can be studied by using Raman spectroscopy.

Analysis of protein degradants
Structures of protein degradants such as oxidized protein, fragments and deamindated proteins can be studied by using Raman spectroscopy.

1. Li, T., Chen, Z., Johnson, J.E. and Thomas, G.J., Jr., Conformations, Interactions, and Thermostabilities of RNA and Proteins in Bean Pod Mottle Virus: Investigation of Solution and Crystal Structures by Laser Raman Spectroscopy, Biochemistry, 31, 6673-6682 (1992).

2. Li, T., Bamford, J.K.H., Bamford, D.H. and Thomas, G.J., Jr., Structural Studies of the Eveloped dsRNA Bacteriophage ø6 of Pseudomonas syringae by Raman Spectroscopy. I. The Virion and Its Membrane, J. Mol. Biol., 230, 461-472 (1993).

(c) 2008 HTL Biosolutions Inc.