Determination of hydroxyproline polypeptides in urine and blood serum by gel filtration

Separation methods for the study of collagen and treatment of collagen disorders

Liquid chromatographic and electrophoretic methods applicable to the separation of collagen and its fragments are reviewed. Special attention is paid to the separation of both stabile and labile crosslinking elements. Identification procedures exploiting the mapping of either collagen alpha-chains or of cyanogen bromide fragments are discussed. These methods can be used for diagnosing inborn errors of collagen metabolism using bioptic or necroptic samples. Analysis of urinary hydroxyproline-containing peptides or the determination of peptidically bound pyridinoline is suitable for measuring the intensity of collagen metabolism.

Clinical significance of free plasma hydroxyproline measurement in metabolic bone disease

Free hydroxyproline was measured in plasma of 67 normal subjects and in 70 patients with bone disease including primary hyperparathyroidism (n = 19), osteoporosis (n = 18), Paget's disease (n = 14), cancer involving bone (n = 8), chronic renal failure (n = 6), and osteomalacia (n = 6), and osteomalacia (n = 5). A good correlation was found between plasma and urinary values of the amino acid in normal subjects (r = 0.66; p less than 0.001). In patients with skeletal disorders a highly significant direct correlation was observed between free plasma hydroxyproline on the one hand and urinary hydroxyproline (r = 0.92; p less than 0.001) and serum alkaline phosphatase activity (r = 0.86; p less than 0.001) on the other, even though there were a few examples of dissociations among these parameters. Free plasma hydroxyproline decreased in the patients with Paget's disease following chronic administration of salmon calcitonin. Following successful parathyroidectomy, free plasma levels of hydroxyproline decreased in all the cases studied. Measurement of free plasma hydroxyproline thus appears to provide a specific index of bone metabolism that may be usefully employed as an alternative to the assay of other markers of bone turnover.

Clinical significance of serum hydroxyproline-containing peptides with special reference to hyproprotein

Serum hydroxyproline-containing peptides were separated into three fractions, i.e. large protein, polypeptide and smaller peptides, by gel filtration on Sephadex G-200. The large protein was presumed to be the C1q subunit of the first component of complement by an immunological analysis. The polypeptide had an electrophoretic mobility corresponding to beta-globulin and its molecular weight was estimated between 35000 and 45000 by gel filtration analysis. The polypeptide might well be defined as hyproprotein. The molecular weight of smaller peptides was estimated between 1400 and 3000. As compared with the control value, hyproprotein levels were significantly increased in rheumatoid arthritis, systemic lupus erythematosus and chronic liver disease. C1q levels were slightly lowered in rheumatoid arthritis and systemic lupus erythematosus, and were slightly increased in chronic liver disease but were not significant. In all patient groups smaller peptides levels remained in the normal range. These results suggest that serum hyproprotein levels are raised in some fibroproliferative disorders, probably reflecting collagen metabolism.

Polymorphism of urinary 4-hydroxyproline-containing polypeptides

Using molecular sieve chromatography on Bio-Gel P-2 and then on Bio-Gel P-30, hydroxyproline-containing urinary polypeptides (molecular weight greater than 1500 daltons) were separated into eight fractions. The three main fractions were separated further on phosphocellulose giving seven, nineteen and twelve peaks, respectively, each containing 4-hydroxyproline. Hypotheses about the origin of certain polypeptides are proposed, which take into account the sequence of type I collagen. Among these 38 polypeptides only one shows a quantitative variation in Paget's bone disease and was thus purified. It consists of equal amounts of glycine, proline and 4-hydroxyproline. This particular polypeptide may originate from the N-terminal propeptide of type I collagen.

The postabsorptive urinary hydroxyproline (spot-HYPRO) in patients with multiple myeloma

The simple postabsorptive urine hydroxyproline (Spot-HYPRO) with dialyzable and non-dialyzable (ND) fractions was measured in 28 patients with multiple myeloma. Myeloma patients with bone disease had higher total Spot-HYPRO and dialyzable fractions (P less than 0.001) than myeloma patients without bone disease or controls. The ND fraction of the Spot-HYPRO was elevated in myeloma patients with renal disease as compared with myeloma patients without renal disease and controls (P less than 0.01). Follow-up studies of ten myeloma patients demonstrated a close correlation between Spot-HYPRO and the dialyzable fraction and the evolution of bone disease. The Spot-HYPRO and its dialyzable fraction constitute a simple, inexpensive, and accurate test for the diagnosis and follow-up of the skeletal disease in patients with multiple myeloma.

Plasma hydroxyproline fractions in patients with dialysis osteodystrophy

Plasma hydroxyproline fractions were measured in 17 normal subjects and in 54 patients on maintenance haemodialysis therapy (MHT) with various degrees of dialysis osteodystrophy. On the basis of both radiological and histological findings these patients were divided into three groups: radiologically normal, histologically normal and those with osteitis fibrosa. The mean total plasma hydroxyproline concentrations were significantly elevated in all groups of MHT patients. However, these increases were mainly due to peptide-bound and free hydroxyproline fractions. The highest values for these two fractions were found in patients with osteitis fibrosa. The free to peptide-bound hydroxyproline ratio was not significantly altered in the majority of patients on dialysis; the mean ratio was significantly lower in patients with osteitis fibrosa when compared with patients with no histological evidence of bone disease. This finding would suggest that there is no inhibition of hydroxyproline catabolism in patients on haemodialysis and the measurements of both free and peptide-bound hydroxyproline were equally sensitive in identifying patients with osteitis fibrosa.

An automatic technique for the routine fractionation of the urinary hydroxyproline containing peptides

A fully automatic method permits fractionation in a Biogel P2 column of the hydroxyproline-containing peptides into two fractions. The alkaline hydrolysis and the colorimetric evaluation of the liberated hydroxyproline are also completely automatic and allow calculation of the percentages of the two fractions. The first one, termed F1 fraction, contains the peptides of molecular weight larger than 1500, while the other, termed F2, contains the smaller peptides. The method was used for 223 assays. The F1 fraction is decreased in cases of Paget's bone disease. It is increased in cases of metastatic cancer of bone. Statistical analysis of the data demonstrates that this techique greatly improves the certainty of diagnosis when coupled to the assay of total hydroxyproline. When both total urinary hydroxyproline and the F1 fraction percentage are increased over threshold values of 485 mumol per 24 h and 28.4% respectively, the probability of the presence of a bone metastasis is 100%.

Fractionation and structure of several hydroxyproline-containing urinary peptides, with special reference to some 3-hydroxyproline-containing peptides

After a preliminary separation of the hydroxyproline-containing peptides on Biogel P 2, the largest peptides are fractionated on phosphocellulose and the smallest ones on QAE-Sephadex. The fractions obtained from QAE-Sephadex are subfractionated on a column of Dowex 50-M-82. The total number of hydroxyproline-containing peptides from human urine is not less than 78. Sixteen di, tri and pentapeptides have been purified, their N-terminal amino acids and amino acid compositions determined and a structure is proposed. 3 of these peptides contain 3-hydroxyproline and one of these 3 peptides probably originates from basement membrane collagen.

Estimation of hydroxylysine in urine and serum of patients with chronic uremia

Free hydroxylysine and hydroxylysing glycosides were separated from urine and serum extracts on cation exchange resin and assayed spectrophotometrically. The method in conjunction with gel filtration in Bio-Gel P2 allowed to separate from urine also polypeptide hydroxylysine and hydroxylysine bound in small molecules of neutral or acidic character. Glycosylgalactosylhydroxylysineand galactosylhydroxylysine were separated by partition and/or ion exchange chromatography. Patients with chronic renal insufficiency had elevated serum levels and urinary excretion of hydroxylysine glycosides with increased excretion of hydroxylysine bound in polypeptides and in small molecules of neutral or acidic character. The excretion of free hydroxylysine was often within normal limits. When compared to values found in normal growing subjects and in adult patients with increased bone turnover and normal renin function the urinary excretion of hydroxylysine glycosides in chronic uremia was more markedly increased than excretion of hydroxyproline polypeptides and total hydroxyproline.