Amino acid racemization reveals differential protein turnover in osteoarthritic articular and meniscal cartilages.

Stabler, Thomas V

Byers, Samuel S

Zura, Robert D

Kraus, Virginia Byers

England

2015-11-10T22:22:06Z

2009

INTRODUCTION: Certain amino acids within proteins have been reported to change from the L form to the D form over time. This process is known as racemization and is most likely to occur in long-lived low-turnover tissues such as normal cartilage. We hypothesized that diseased tissue, as found in an osteoarthritic (OA) joint, would have increased turnover reflected by a decrease in the racemized amino acid content. METHODS: Using high-performance liquid chromatography methods, we quantified the L and D forms of amino acids reported to racemize in vivo on a biological timescale: alanine, aspartate (Asp), asparagine (Asn), glutamate, glutamine, isoleucine, leucine (Leu), and serine (Ser). Furthermore, using a metabolically inactive control material (tooth dentin) and a control material with normal metabolism (normal articular cartilage), we developed an age adjustment in order to make inferences about the state of protein turnover in cartilage and meniscus. RESULTS: In the metabolically inactive control material (n = 25, ages 13 to 80 years) and the normal metabolizing control material (n = 19, ages 17 to 83 years), only Asp + Asn (Asx), Ser, and Leu showed a significant change (increase) in racemization with age (P < 0.01). The age-adjusted proportions of racemized to total amino acid (D/D+L expressed as a percentage of the control material) for Asx, Ser, and Leu when compared with the normal articular cartilage control were 97%, 74%, and 73% in OA meniscal cartilage and 97%, 70%, and 78% in OA articular cartilage. We also observed lower amino acid content in OA articular and meniscal cartilages compared with normal articular cartilage as well as a loss of total amino acids with age in the OA meniscal but not the OA articular cartilage. CONCLUSIONS: These data demonstrate comparable anabolic responses for non-lesioned OA articular cartilage and OA meniscal cartilage but an excess of catabolism over anabolism for the meniscal cartilage.

https://www.ncbi.nlm.nih.gov/pubmed/19267899

ar2639

1478-6362

https://hdl.handle.net/10161/10861

eng

Springer Science and Business Media LLC

Arthritis Res Ther

10.1186/ar2639

Adult

Age Factors

Aged

Aged, 80 and over

Amino Acids

Cartilage, Articular

Chromatography, High Pressure Liquid

Dentin

Humans

Isomerism

Menisci, Tibial

Middle Aged

Osteoarthritis, Knee

Amino acid racemization reveals differential protein turnover in osteoarthritic articular and meniscal cartilages.

Journal article

Kraus, Virginia Byers|0000-0001-8173-8258

https://www.ncbi.nlm.nih.gov/pubmed/19267899

R34

2

Clinical Science Departments

Duke

Duke Molecular Physiology Institute

Faculty

Institutes and Centers

Medicine

Medicine, Rheumatology and Immunology

Orthopaedics

Pathology

School of Medicine

Published

11