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Biomedical subjects

Q Zhao

Publications and source records attributed to Q Zhao.

At least 163 records · Page 9Linked to original sources
PubMed1998

[Expression, purification and characterization of recombinant human cyclophilin A].

Plasmid-derived expression of the human CyPA in E. coli would make it possible to obtain ample protein quantities and to avoid difficult task of obtaining human tissues for protein purification. The cDNA encoding human CyPA from MT4 lymph cell line has been cloned and an expression vector (pET11/CyPA) has been constructed under control of the T7 promoter for efficient expression in E. coli. The recombinant CyPA is produced at 41% of total soluble cell protein, and showed the peptidyl-prodyl cis-trans isomerase activity.

Cell Line↗
PubMed1998

[Study on the inclusion of isodoniol-beta-cyclodextrin].

The inclusion compound of isodoniol-beta-cyclodextrin was prepared by the liquidphase method in aqueous solution. And it was confirmed by thinlayer chromatography, differentical thermal analysis and specific rotation. The change (delta A) of ultraviolet spectrum was determined. The composition ratio of the inclusion compound between isodoniol and beta-CD was obtained by the continuous variation method.

Cyclodextrins↗
PubMed1997

Hydrogen bonding at the active site of delta 5-3-ketosteroid isomerase.

The solution secondary structure of the highly active Y55F/Y88F "Tyr-14-only" mutant of delta 5-3-ketosteroid isomerase complexed with 19-nortestosterone hemisuccinate has been shown to consist of three helices, a six-stranded mixed beta-sheet, and five turns. The steroid binds near the general acid, Tyr-14, on helix 1, near the general base, Asp-38, on the first strand of the beta-sheet, and on the hydrophobic face of the beta-sheet [Zhao, Q., Abeygunawardana, C., & Mildvan, A. S. (1997) Biochemistry 36, 3458-3472]. On this hydrophobic face, Asp-99 is the only polar residue. Free isomerase shows a deshielded exchangeable proton resonance at 13.1 ppm assigned to the N epsilon H of neutral His-100. Its fractionation factor (phi = 0.79) and slow exchange with solvent suggest it to be buried or involved in an H-bond. The binding of dihydroequilenin or estradiol to isomerase induces the appearance of two additional deshielded proton resonances, one at 18.2 ppm assigned to the gamma-carboxyl proton of Asp-99, and the other, at 11.6 ppm, assigned to the zeta-OH proton of Tyr-14. While mutation of Asp-99 to Ala results in the disappearance of only the resonance near 18 ppm [Wu, R. W., Ebrahemian, S., Zwrotny, M. E., Thornberg, L. D., Perez-Alverado, G. C., Brothers, P., Pollack, R. M., & Summers, M. F. (1997) Science 276, 415-418], both of these resonances disappear in mutants lacking Tyr-14, suggesting an H-bonded catalytic diad, Asp-99-COOH--Tyr14-OH--O-steroid enolate. The catalytic diad is further supported by NOEs from the beta 1 and beta 2 protons of Asp-99 to the epsilon protons of Tyr-14, and from the zeta-OH proton of Tyr-14 to the gamma-carboxyl proton of Asp-99, indicating close proximity of these two residues, and by other data from the literature. A strong, low-barrier H-bond between Asp-99 and Tyr-14 is indicated by the 6.2 ppm deshielding, low fractionation factor (phi = 0.34) and slow exchange of the resonance at 18.2 ppm. A normal H-bond between Tyr-14 and the steroid is indicated by the 1.8 ppm deshielding, fractionation factor of 0.97 and the slow exchange of the resonance at 11.6 ppm. It is suggested that the 10(4.7)-fold contribution of Tyr-14 to catalysis is made possible by strong H-bonding from Asp-99 in the catalytic diad which strengthens general acid catalysis by Tyr-14. It is also noted that highly deshielded proton resonance on enzymes between 15 and 20 ppm, assigned to low-barrier H-bonds, generally involve carboxyl groups.

Aspartic Acid↗
PubMed1997

Nerve regeneration in a 'pseudo-nerve' graft created in a silicone tube.

The pseudo-nerve, which contains longitudinal Schwann cell columns without axons and surrounded by perineurium-like tissue but no axons (Q. Zhao, L.B. Dahlin, M. Kanje, G. Lundborg, Brain Res. 592 (1992) 106-114), was applied as a graft to repair nerve defect in rats. Creation of the pseudo-nerve was accomplished by inserting the proximal and distal stumps of a cut sciatic nerve into a silicone tube. The proximal insert was cut far proximally to prevent axons from entering the tube. After 4 weeks, the pseudo-nerve was harvested, trimmed into a 10-mm long graft and transplanted into a corresponding defect of the contralateral sciatic nerve. Nerve regeneration through the pseudo-nerve was examined by pinch reflex test and neurofilament staining after 6 days or by morphology after 4, 6 or 8 weeks. The results showed that the pseudo-nerve could induce nerve regeneration to a similar extend as a real nerve graft. The neurobiological composition of the pseudo-nerve and the factors influencing its formation were also studied. By double staining of S-100 and laminin we found that the longitudinally organized Schwann cell columns in the pseudo-nerve were surrounded by basal laminae and ensheathed by a layer of vascularized perineurium-like tissue. Macrophages (ED1 and ED2) and their products interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) were constantly present in the pseudo-nerve. Besides, the size of tube was a crucial factor in influencing pseudo-nerve formation, e.g. a thicker pseudo-nerve was formed in tubes with larger diameters or shorter gap lengths. No pseudo-nerve was formed when the gap was 15 mm long. When both proximal and distal inserts were isolated nerve segments the pseudo-nerve was still formed but thin, probably because of compromised vascular supply. Taken together, the results suggested that the pseudo-nerve contains the essential neurobiological elements to induce successful axonal elongation.

Animals↗
PubMed1997

The second finger of Urbs1 is required for iron-mediated repression of sid1 in Ustilago maydis.

The urbs1 gene encodes a transcriptional regulator of siderophore biosynthesis in Ustilago maydis. Biological and DNA-binding activities of the two putative zinc-finger motifs of Urbs1 were studied by analyzing mutants containing altered finger domains. The mutated urbs1 alleles from three previously described N'-methyl-N'-nitro-N-nitrosoguanidine (NTG) mutants were mapped and cloned by a gap-repair procedure. Sequence analyses revealed single amino acid substitutions in two of the NTG mutants. Both mutations (G-507 to D in urbs1-1 and P-491 to L in urbs1-3), which are located in the Urbs1 C-terminal finger domain, reduced DNA-binding activity by 10-fold and were sufficient to confer a urbs1-minus phenotype. The third NTG urbs1 mutant (urbs1-2) also contained a mutation in one of the conserved amino acids (P-518 to S) in the C-terminal finger domain, but this mutation alone was not sufficient to confer a urbs1-minus phenotype. A second frame shift mutation was identified in urbs1-2 and is necessary for the urbs1-minus phenotype. In an analysis of the function of the N-terminal finger of Urbs1, the conserved amino acid Arg-350 was mutated to leucine. A Urbs1 protein with this mutation complemented a urbs1 null mutant strain. By contrast, a similar mutation in the C-terminal domain abolished the ability of Urbs1 to regulate siderophore biosynthesis and greatly reduced its ability to bind target DNA.

Amino Acid Sequence↗
PubMed1997

The Vav binding site (Y315) in ZAP-70 is critical for antigen receptor-mediated signal transduction.

Stimulation of antigen receptors in T and B cells leads to the activation of the Src and Syk families of protein tyrosine kinases (PTK). These PTKs subsequently phosphorylate numerous intracellular substrates, including the 95-kD protooncogene product Vav. Vav is essential for both T and B cell development and T and B cell antigen receptor-mediated signal transduction. After receptor ligation, Vav associates with phosphorylated Syk and ZAP-70 PTKs, an interaction that depends upon its SH2 domain. Here we demonstrate that a point mutation of tyrosine 315 (Y315F) in ZAP-70, a putative Vav SH2 domain binding site, eliminated the Vav- ZAP-70 interaction. Moreover, the Y315 mutation impaired the function of ZAP-70 in antigen receptor signaling. Surprisingly, this mutation also resulted in marked reduction in the tyrosine phosphorylation of ZAP-70, Vav, SLP-76, and Shc. These data demonstrate that the Vav binding site in ZAP-70 plays a critical role in antigen receptor-mediated signal transduction.

Adaptor Proteins, Signal Transducing↗
PubMed1997

NMR studies of the secondary structure in solution and the steroid binding site of delta5-3-ketosteroid isomerase in complexes with diamagnetic and paramagnetic steroids.

Backbone and side chain resonances of steroid-bound delta5-3-ketosteroid isomerase (EC 5.3.3.1), a homodimeric enzyme with 125 residues per monomer, have been assigned by heteronuclear NMR methods with the 15N- and 13C-labeled enzyme. The secondary structure in solution of steroid-bound isomerase, based on interproton NOE's and differences in chemical shifts of backbone H alpha, C alpha, C beta, and CO resonances from random coil values, consists of two alpha-helices (residues 5-21, 48-60), one 3(10) helix (residues 23-30), seven beta-strands (residues 34-38, 44-47, 62-67, 71-73, 78-87, 92-104, and 111-116), and five turns (residues 39-42, 74-77, 88-91, 105-108, and 119-122). Thus isomerase consists of 30% helix, 38% beta-sheet, and 16% turns. The remaining 20 residues (16%) are assumed to form coils. With the exception of a parallel interaction between beta-strands 1 and 7, all beta-strand interactions are antiparallel, forming both a beta-hairpin (beta1, beta2) and a four-stranded beta-sheet in which the first strand is interrupted (beta3-beta4, beta5, beta6, beta7). 1H-15N HSQC titrations of the free enzyme with the substrate analog 19-nortestosterone hemisuccinate revealed steroid-induced changes in backbone 15N and NH chemical shifts throughout the enzyme, with maximal effects on helix I (Val-15), beta-strand 1 of the beta-hairpin (Asp-38), the loop between helix 3 and beta-strand 3 (Leu-61), beta-strand 3 (Ala-64), beta-strand 5 (Phe-82, Ser-85, Glu-87), beta-strand 6 (Ile-98), and beta-strand 7 (Ala-114, Phe-116) of the beta-sheet, thus indicating the secondary structural components involved in steroid binding. These effects include regions near the catalytic residues Tyr-14 and Asp-38 which function as the general acid and base, respectively, in the ketosteroid isomerase reaction. Intermolecular NOE's between 19-nortestosterone hemisuccinate and isomerase indicate that the steroid binds near alpha-helices 1 and 3, which form one wall of the active site, and one end of the four-stranded beta-sheet which forms the other wall. Consistent with these observations, doxyldihydrotestosterone, a steroid that is spin-labeled at its solvent-exposed end [Kuliopulos, A., Westbrook, E. M., Talalay, P., & Mildvan, A. S. (1987) Biochemistry 26, 3927-3937], induced the selective attenuation in the 1H-15N HSQC spectra of cross peaks of residues at the end of helix 3 (Ser-58, Leu-59, Lys-60, Leu-61), beta-strand 5 (Val-84, Ser-85), and beta-strand 6 (Val-95), due to the proximity of the nitroxide radical to the backbone 15N and NH nuclei of these residues, thus confirming the location of the D ring of the bound steroid and defining the mouth of the active site.

Amino Acid Sequence↗
PubMed1997

Mixed-backbone oligonucleotides as second generation antisense oligonucleotides: in vitro and in vivo studies.

Antisense oligonucleotides are being evaluated in clinical trials as novel therapeutic agents. To further improve the properties of antisense oligonucleotides, we have designed mixed-backbone oligonucleotides (MBOs) that contain phosphorothioate segments at the 3' and 5' ends and have a modified oligodeoxynucleotide or oligoribonucleotide segment located in the central portion of the oligonucleotide. Some of these MBOs indicate improved properties compared with phosphorothioate oligodeoxynucleotides with respect to affinity to RNA, RNase H activation, and anti-HIV activity. In addition, more acceptable pharmacological, in vivo degradation and pharmacokinetic profiles were obtained with these MBOs.

Animals↗
PubMed1997

Unexpected genetic and structural relationships of a long-forgotten flavoenzyme to NAD(P)H:quinone reductase (DT-diaphorase)

A mammalian cytosolic FAD-dependent enzyme that catalyzes the reduction of quinones by N-ribosyl- and N-alkyldihydronicotinamides, but not by NADH, NADPH, or NMNH (reduced nicotinamide mononucleotide), was isolated from bovine kidney more than 30 years ago [S. Liao, J. T. Dulaney and H. G. Williams-Ashman (1962) J. Biol. Chem. 237, 2981-2987]. This enzyme is designated here as quinone reductase type 2 (QR2). Bovine QR2 is a homodimer that migrates on SDS/PAGE at approximately 22 kDa. Three tryptic peptides of bovine QR2 (representing 39 amino acids) showed 43% identity to human NAD(P)H:quinone reductase (DT-diaphorase; EC 1.6.99.2), here designated QR1 and 82% identity to a related human cDNA clone [called hNQO2 by A. K. Jaiswal, P. Burnett, M. Adesnik and O. W. McBride (1990) Biochemistry 29, 1899-1906], and designated here as hQR2. The protein encoded by the latter cDNA did not show QR activity when tested with conventional nicotinamide nucleotides. The unexpected high homology between the old flavoenzyme and hQR2 prompted us to clone and overexpress hQR2. The properties of hQR2 were identical to those of the flavoenzyme described by S. Liao and H. G. Williams-Ashman, thus establishing their genetic identity. Recombinant human QR2: (i) reacts with N-ribosyl- and N-alkyldihydronicotinamides, but not with NADH, NADPH, or NMNH; (ii) is very weakly inhibited by dicumarol or Cibacron blue; (iii) is very potently inhibited by benzo[a]pyrene. The x-ray crystal structure of rat QR1 shows that the 43 amino acid C-terminal tail of QR1 provides the binding site for the hydrophilic portions of NADH and NADPH. In the absence of this binding site in QR2, the enzyme retains the essential catalytic machinery, including affinity for FAD, but cannot bind phosphorylated hydride donors.

Amino Acid Sequence↗
PubMed1997

Mixed backbone antisense oligonucleotides: design, biochemical and biological properties of oligonucleotides containing 2'-5'-ribo- and 3'-5'-deoxyribonucleotide segments.

We have designed and synthesized mixed backbone oligonucleotides (MBOs) containing 2'-5'-ribo- and 3'-5'-deoxyribonucleotide segments. Thermal melting studies of the phosphodiester MBOs (three 2'-5'linkages at each end) with the complementary 3'-5'-DNA and -RNA target strands suggest that 2'-5'-ribonucleoside incorporation into 3'-5'-oligodeoxyribonucleotides reduces binding to the target strands compared with an all 3'-5'-oligodeoxyribonucleotide of the same sequence and length. Increasing the number of 2'-5'linkages (from six to nine) further reduces binding to the DNA target strand more than the RNA target strand [Kandimalla,E.R. and Agrawal,S. (1996)Nucleic Acids Symp. Ser., 35, 125-126]. Phosphorothioate (PS) analogs of MBOs destabilize the duplex with the DNA target strand more than the duplex with the RNA target strand. Circular dichroism studies indicate that the duplexes of MBOs with the DNA and RNA target strands have spectral characteristics of both A- and B-type conformations. Compared with the control oligonucleotide, MBOs exhibit moderately higher stability against snake venom phosphodiesterase, S1 nuclease and in fetal calf serum. Although 2'-5'modification does not evoke RNase H activity, this modification does not effect the RNase H activation property of the 3'-5'-deoxyribonucleotide segment adjacent to the modification. In vitro studies with MBOs suggest that they have lesser effects on cell proliferation, clotting prolongation and hemolytic complement lysis than do control PS oligodeoxyribonucleotides. PS analogs of MBOs show HIV-1 inhibition comparable with that of a control PS oligodeoxyribonucleotide with all 3'-5'linkages. The current results suggest that a limited number of 2'-5'linkages could be used in conjunction with PS oligonucleotides to further modulate the properties of antisense oligonucleotides as therapeutic agents.

Animals↗
PubMed1997

Parallel expression of Sox9 and Col2a1 in cells undergoing chondrogenesis.

To assess the role of the transcription factor Sox9 in cartilage formation we have compared the expression pattern of Sox9 and Col2a1 at various stages of mouse embryonic development. Expression of Col2a1 colocalized with expression of Sox9 in all chondroprogenitor cells. In the sclerotomal compartment of somites the onset of Sox9 expression preceded that of Col2a1. A perfect correlation was also seen between high levels of Sox9 expression and high levels of Col2a1 expression in chondrocytic cells. However, no Sox9 expression was detected in hypertrophic chondrocytes; only low levels of Col2a1 RNA were found in the upper hypertrophic zone. Coexpression of Sox9 and Col2a1 was also seen in the notochord. At E11.5 Sox9 expression in the brain and spinal neural tube was more widespread than that of Col2a1 although at E14.5 Sox9 and Col2a1 transcripts were colocalized in discrete areas of the brain. Distinct differences between Sox9 and Col2a1 expression were observed in the otic vesicle at E11.5. At E8.5, expression of Sox9 but not of Col2a1 was seen in the dorsal tips of the neural folds and after neural tube closure also in presumptive crest cells emigrating from the dorsal pole of the neural tube. No Col2a1 expression was detected in gonadal ridges in which high levels of Sox9 expression were detected. Together with our previous results showing that the chondrocyte-specific enhancer element of the Col2a1 gene is a direct target for Sox9, these results suggest that Sox9 plays a major role in expression of Col2a1. The correlation between high expression levels of Sox9 and high expression levels of Col2a1 in chondrocytes suggests the hypothesis that high levels of Sox9 are needed for full expression of the chondrocyte phenotype; lower levels of Sox9 such as in neuronal tissues which are also associated with lower expression levels of Col2a1 would be compatible with other cell specifications.

Animals↗
PubMed1997

Opioid peptides derived from hemoglobin: hemorphins.

Investigation of hemoglobin peptic hydrolysate has revealed the presence of biologically active peptides with affinity for opioid receptors. Two peptides, VV-hemorphin-7 and LVV-hemorphin-7, were resolved by a combination of size exclusion and reversed phase HPLC. A new spectroscopic method based on the second order derivative spectra analysis of aromatic amino acids has been developed. This method allows qualitative and quantitative evaluation of hemorphins generated by peptic hemoglobin hydrolysis. Using this method, a kinetic study of hemorphins appearance has been undertaken. In this paper, we also evidenced the generation of VV-hemorphin-7 from globin by peritoneal macrophages. In regard to this result, the putative physiological role of hemorphins is discussed.

Amino Acid Sequence↗
PubMed1997

Structural analysis of the mouse prosaposin (SGP-1) gene reveals the presence of an exon that is alternatively spliced in transcribed mRNAs.

SGP-1/prosaposin can be secreted or targeted to the lysosomes where it is processed into smaller saposins A, B, C, and D required for the hydrolysis of glycosphingolipids. The deficiency of saposins B and C results in variant forms of metachromatic leukodystrophy and Gaucher's disease, respectively, which are characterized by lysosomal storage of undegraded glycosphingolipids. A required step to correct these genetic defects, or to understand the targeting mechanism of SGP-1 to the lysosomes, or to the extracellular space as well as its interaction with specific glycosphingolipids, is the analysis of the gene encoding this protein. Thus our investigation dealt with the molecular cloning of the mouse SGP-1 gene. Sequence analysis revealed that the mouse SGP-1 gene consists of 15 exons ranging from nine base pairs to 298 base pairs and 14 introns, which ranged from 89 base pairs to >8 kb in length. Our data show that saposin A is encoded by the exons 3, 4, and 5, saposin B by exons 6, 7, 8, and 9, saposin C by exons 10 and 11, and saposin D by exons 12, 13, and 14. The translation start codon is located within exon 1, and the translation stop codon is located within exon 15. The exon/intron boundaries were in accordance to the AG/GT consensus sequences. Our data also revealed that the SGP-1 gene has an exon consisting of the nine base pairs (CAG GAT CAG) encoding the three amino acids of saposin B, which may be alternatively spliced in the SGP-1 mRNA. The presence of the different forms of alternatively spliced mRNAs in various tissues was analyzed by RT-PCR. This approach demonstrated that prosaposin mRNAs of brain, heart, and muscle contain the nine base pairs of exon 8, whereas the transcripts from testis, lung, pancreas, spleen, and kidney do not contain this exon 8. Sequence comparison between the human and mouse prosaposin showed that exon 11 of mouse SGP-1 consists of 279 base pairs, whereas the human prosaposin gene consists of 187 base pairs. The extra 93 base pairs encode 31 amino acids corresponding to a proline-rich region located between saposin C and saposin D in the mouse prosaposin molecule. Finally, the availability of these genomic clones provides a starting point for further studies on the genetic role of specific sequences on the structure and function of SGP-1/prosaposin and its derived saposin proteins. In conclusion, we cloned and sequenced the mouse prosaposin (SGP-1) gene. The structural analysis of this gene revealed the presence of an exon that is alternatively spliced in transcribed mRNAs in a tissue-specific manner.

Alternative Splicing↗
PubMed1997

Effect of transient focal ischemia on blood-brain barrier permeability in the rat: correlation to cell injury.

Prolonged ischemia is known to damage the blood-brain barrier, causing an increase in vascular permeability to proteins. We studied the time course of extravasation of endogenous albumin in rats after 1 and 2 h of middle cerebral artery (MCA) occlusion followed by 6, 12, and 24 h of recirculation. In a separate group of rats that had undergone 1 h of MCA occlusion and 6 h of recirculation, influx of [14C]aminoisobutyric acid (AIB) from blood to brain was also measured. After 1 h of occlusion followed by 6 h of recirculation, neuronal damage was evident in caudoputamen, but there were no signs of blood-brain barrier leakage to either AIB or albumin. At 12 h, the caudoputamen contained extravasated albumin, and at 24 h extravasation was extended to the somatosensory cortex. Animals subjected to 2 h of MCA occlusion showed albumin extravasation in caudoputamen already at 6 h of recirculation, and at 12 and 24 h albumin was abundant in the major part of the right hemisphere. This study suggests that damage to neurons precedes leakage of the blood-brain barrier. Even a relatively short period of ischemia such as 1 h will result in markedly increased vascular permeability. However, a longer transient ischemic insult disrupts the blood-brain barrier earlier than a shorter one.

Albumins↗
PubMed1997

Rat sciatic nerve regeneration through a micromachined silicon chip.

The capacity of regenerating nerve fibres to grow through a perforated silicon chip was tested using the silicone chamber model for nerve regeneration. The chips were fabricated as circular membranes, 4 mm in diameter, thickness 60 microns, with a perforated area, 2 mm in diameter, in the centre. Three types of chips were fabricated utilizing anisotropic etching. The chips were glued with silicone adhesive between two halves of silicone rubber tubing (total length 8 mm, inner diameter 1.8 mm, outer diameter 3.0 mm) which was used to bridge a 4 mm gap between the proximal and distal nerve stumps of a transected rat sciatic nerve. The capacity of regenerating nerve fibres to grow through the holes of the chip was analysed by light and scanning electron microscopy after 4 or 16 weeks of regeneration. Furthermore, the muscle contractility force of the gastrocnemius muscle was measured after 16 weeks of regeneration and compared as a percentage of the contralateral uninjured side. Nerves generated through chips with hole diameters of 10 or 50 microns were morphological and functional failures. The nerve structures distal to chips with hole diameters of 100 microns contained many myelinated nerve fibres in a minifascicular pattern after both 4 and 16 weeks of regeneration. The muscle contractility force was 56% of that of contralateral control muscles.

Animals↗
PubMed1997

Investigation of inhibition angiotensin-converting enzyme (ACE) activity and opioid activity of two hemorphins, LVV-hemorphin-5 and VV-hemorphin-5, isolated from a defined peptic hydrolysate of bovine hemoglobin.

Two peptides, LVV-hemorphin-5 and VV-hemorphin-5, were isolated from a defined peptic bovine hemoglobin hydrolysate by reversed-phase HPLC. These peptides were identified as 31-38 and 32-38 fragments of beta chain of bovine hemoglobin. Their inhibitory activity towards angiotensin-converting enzyme and opioid potency were determined. Since their amino acid sequences show close homology with spinorphin, which is found in human cerebrospinal fluid and in the bovine spinal cord, the possible physiological role in vivo of these peptides was discussed.

Amino Acid Sequence↗
PubMed1997

Hemorphin peptides are released from hemoglobin by cathepsin D. radioimmunoassay against the C-part of V-V-hemorphin-7: an alternative assay for the cathepsin D activity.

In order to investigate the putative physiological role of the in vivo release of hemorphins from hemoglobin in tissues, an immunological approach was developed. Specific and sensitive antiserum were raised against the C-part of the V-V-hemorphin-7. The antisera recognized to the same extent the related hemorphins V-V-hemorphin-7 and L-V-V-hemorphin-7. The validity of our immunological approach was analyzed by studying the in vitro release of hemorphin from hemoglobin by cathepsin D and compared to the pepsin hydrolysis. These two enzymes led to the release of these same products suggesting that cathepsin D acted as an accurate pepsin-like enzyme. Moreover, considering the poor sensitivity of the available methods of detection for the in vitro Cathepsin D activity, our specific and sensitive V-V-hemorphin-7 radioimmunoassay seems to be a useful alternative assay for this enzymatic activity.

Amino Acid Sequence↗