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PubMed2001

Fluorometric determination of N-terminal prolyl dipeptides, proline and hydroxyproline in human serum by pre-column high-performance liquid chromatography using 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsufonyl chloride.

A highly sensitive HPLC method for the determination of prolyl dipeptides, Pro and Hyp in serum was developed. After deproteinization of serum and pretreatment with o-phthalaldehyde, the analytes were derivatized with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride at 70 degrees C for 10 min. The fluorescent derivatives of prolyl dipeptides, Pro and Hyp, were separated on tandem reversed-phase columns by a gradient elution at 55 degrees C and detected by fluorescence measured at 318 nm (excitation) and 392 nm (emission). The detection limits for prolyl dipeptides were 2-5 fmol/injection (S/N=3). Pro-Hyp, Pro-Gly and Pro-Pro were identified as serum prolyl dipeptides. The within-day and between-day relative standard deviations were 1.5-7.9 and 2.4-10.8%, respectively. The recoveries were in the range of 90.8-97.3%. The concentrations of Pro-Hyp, Pro-Gly, Pro-Pro, Pro and Hyp in normal human serum (n = 10) were 0.64+/-0.35, 0.078+/-0.047, 0.022+/-0.016, 177.0+/-43.0 and 11.1+/-3.5 microM, respectively. The concentrations of Pro-Hyp and Pro-Pro in serum of a patient with bone metastases of prostatic cancer were about three times and 50 times, respectively, higher than those in normal human serum.

Chromatography, High Pressure Liquid↗
PubMed1999

Highly sensitive determination of N-terminal prolyl dipeptides, proline and hydroxyproline in urine by high-performance liquid chromatography using a new fluorescent labelling reagent, 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride.

A highly sensitive pre-column HPLC method for simultaneous determination of prolyl dipeptides, Pro and Hyp in urine was developed. The analytes were labelled with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride at 70 degrees C for 20 min. The derivatives separated on tandem reversed-phase columns by a gradient elution and were monitored with fluorescence detection at 318 nm (excitation) and 392 nm (emission). The detection limits for prolyl dipeptides, Pro and Hyp were 1-5 fmol/injection (S/N = 3). Urine samples were treated with o-phthalaldehyde, followed by purification on a Bond Elut C18 column before conducting the labelling reaction. Pro-Hyp, Pro-Gly and Pro-Pro were identified as prolyl dipeptides in urine. The within-day and between-day relative standard deviations were 1.5-4.8 and 1.7-5.8%, respectively. The concentrations of Pro-Hyp, Pro-Gly, Pro-Pro, Pro and Hyp in normal human urine were 97.6 +/- 28.2, 2.74 +/- 1.48, 2.08 +/- 1.13, 6.71 +/- 3.34 and 2.30 +/- 1.59 nmol/mg creatinine, respectively.

Chromatography, High Pressure Liquid↗
PubMed2003

Effect of 3-hydroxyproline residues on collagen stability.

Collagen is an integral part of many types of connective tissue in animals, especially skin, bones, cartilage, and basement membranes. A fibrous protein, collagen has a triple-helical structure, which is comprised of strands with a repeating Xaa-Yaa-Gly sequence. l-Proline (Pro) and 4(R)-hydroxy-l-proline (4-Hyp) residues occur most often in the Xaa and Yaa positions. The 4-Hyp residue is known to increase markedly the conformational stability of a collagen triple helix. In natural collagen, a 3(S)-hydroxy-l-proline (3-Hyp) residue occurs in the sequence: 3-Hyp-4-Hyp-Gly. Its effect on collagen stability is unknown. Here, two host-guest peptides containing 3-Hyp are synthesized: (Pro-4-Hyp-Gly)(3)-3-Hyp-4-Hyp-Gly-(Pro-4-Hyp-Gly)(3) (peptide 1) and (Pro-4-Hyp-Gly)(3)-Pro-3-Hyp-Gly-(Pro-4-Hyp-Gly)(3) (peptide 2). The 3-Hyp residues in these two peptides diminish triple-helical stability in comparison to Pro. This destabilization is small when 3-Hyp is in the natural Xaa position (peptide 1). There, the inductive effect of its 3-hydroxyl group diminishes slightly the strength of the interstrand 3-HypC=O.H-NGly hydrogen bond. The destabilization is large when 3-Hyp is in the nonnatural Yaa position (peptide 2). There, its pyrrolidine ring pucker leads to inappropriate mainchain dihedral angles and interstrand steric clashes. Thus, the natural regioisomeric residues 3-Hyp and 4-Hyp have distinct effects on the conformational stability of the collagen triple helix.

Collagen↗