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Facile preparation of titanium phosphate-modified chitosan for selective capture of phosphopeptides

Authors

  • Feng Shen,

    1. Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing, P. R. China
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    • These authors contributed equally to this work.

  • Yufeng Hu,

    1. Department of Environmental Sciences and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing, P. R. China
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    • These authors contributed equally to this work.

  • Ping Guan,

    1. Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing, P. R. China
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  • Xueqin Ren

    Corresponding author
    1. Department of Environmental Sciences and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing, P. R. China
    • Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing, P. R. China
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Correspondence: Dr. Xueqin Ren, Department of Environmental Sciences and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, P. R. China

E-mail: renxueqin@cau.edu.cn

Fax: 86-10-62731016

Abstract

A facile two-step method for preparing chitosan-based immobilized metal ion affinity chromatography was developed. First, chitosan was phosphorylated by esterification with phosphoric acid, and then titanium was chelated onto the phosphorylated chitosan. The obtained chitosan-based titanium immobilized metal ion affinity chromatography was ultrafine microparticles and had good dispersibility in acidic buffer. The selectivity and sensitivity were evaluated by phosphopeptide enrichment of mixtures of α-casein and bovine serum albumin. The enriched peptides were analyzed by mass spectrum. Enrichment protocols were optimized and the optimum-loading buffer was 80% acetonitrile with 1% trifluoroacetic acid. With α-casein concentration as low as 2 pmol, 12 phosphopeptides were detected with considerably high intensity from the digest mixtures of α-casein and bovine serum albumin with molar ratio of 1:200. The microparticles was also applied in real biological samples, 29 phosphoproteins containing 40 phosphorylated sites were identified from salt-stressed Arabidopsis thaliana leaves.

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