Abstract The prolidase activity in serum and in erythro- cytes was measured in 28 healthy mothers and in the cord blood of their newborn babies in using a modified Chinard method. 45 healthy non-pregnant women aged between 15–36 years formed a control group. Biochemi- cal parameters (CK, BUN, C-peptid, AFP, Uric acid) were also measured. The serum and erythrocyte proli- dase activities in maternal blood were 45.8±13.4 U/L and 37.8±2.7 U/g Hb respectively. There was no signifi- cant difference in the enzyme activities between preg- nant women and the control group (p>0.05). However serum and erythrocyte prolidase activity in cord blood (20.3±8.2 U/L and 31.6±7.3 U/g Hb) was significantly different when compared with control group (53.4± 14.7 U/L in serum and 42.3±10.3 U/g Hb in erythrocyte, p<0.001). There was a significant correlation between maternal and cord blood serum enzyme activity (r: 0.76 p<0.01). This correlation was also shown in erythrocyte prolidase activities of both groups (r: 0.49, p<0.05). Cord blood prolidase activity was positively correlated with birth weight (r: 0.89, p<0.01). Prolidase activity in cord blood was low even though collagen turnover is in- creased in fetal growth. Keywords Prolidase · Cord blood · Maternal blood Introduction Connective tissue protein collagen comprise one-third of total body protein. Prolidase (E.C: 3.4.13.9) is an imino- dipeptidase which can catalyse the rapid hydrolysis of the peptide bond involving the imino nitrogen of proline or hydroxyproline [3, 7, 12]. Because of the high propor- tion of the iminoacids in collagen (25% Pro and Hyp to- gether), this enzyme plays an important role in its degra- dation and its activity might be correlated with the rate of collagen degradation [10]. Since the collagen turnover rate is expected to be high during fetal growth, the level of prolidase activity may reflect fetal maturation. The presence of this enzyme in various tissues has been demonstrated [9]. However there is no report con- cerning prolidase activity in maternal and cord blood. A recent study has shown prolidase activity in amniotic fluid and its activity level was positively correlated with the body weight and lecithin levels in mature newborns [7]. We investigated the serum and erythrocyte prolidase activities of healthy pregnant women and their new-born. In addition CK, BUN, c-peptide, AFP and Uric acid were measured in the same groups. These values were compared with a control group of healty non-pregnant women. Material and method We studied maternal 28 healthy mothers and their newborn and 45 non-pregnant control women aged between 15–36 at Gaziantep University, Faculty of Medicine, Department of Obstetrics and Gynecology. 5 ml samples of venous blood were placed in a cen- trifuge tube and spun for 5 min at 2000 rpm. Biochemical para- meters were measured on the same day. For hemolysate, venous blood was collected into heparinized tubes. After centrifugation at 2000 rpm for three min, plasma was separeted. Erythrocytes were washed three times with saline (0.9%). 2.5 mM MnCl 2 was used as a hemolysing reagent. The hemolysate and serum were stored at –20°C. Serum prolidase assay:Serum was diluted 40 fold with 2.5 mmole/L Mn ++ , 40 mmole/L Trizma HCl buffer (pH : 8) and E.S. Namiduru ( ✉ ) Department of Biochemistry and Clinical Biochemistry, University of Gaziantep, Faculty of Medicine, Department of Biochemistry, 27310, Sehitkamil, Gaziantep, Turkey e-mail: enamiduru@hotmail.com Tel.: 0090-342-3601200/3206, Fax: 0090-342-3601617 Y. Özdemir Department of Biochemistry and Clinical Biochemistry, Faculty of Medicine, University of Harran, S. Urfa, Turkey I. Kutlar · Ü. Ersoy Obstetrics and Gynecology, Faculty of Medicine, University of Gaziantep, Turkey Arch Gynecol Obstet (2001) 265:73–75 © Springer-Verlag 2001 ORIGINAL ARTICLE E.S. Namiduru · Y. Özdemir · I. Kutlar · Ü. Ersoy A study of prolidase in mothers, their newborn babies and in non-pregnant controls Received: 15 June 2000 / Accepted: 4 October 2000