Biomedical subjects

T Kokubo

Publications and source records attributed to T Kokubo.

At least 91 records · Page 5Linked to original sources

PubMed1999

Effect of bioactive filler content on mechanical properties and osteoconductivity of bioactive bone cement.

We took three types of bioactive bone cement (designated AWC, HAC, and TCPC), each with a different bioactive filler, and evaluated the influence of each filler on the mechanical properties and osteoconductivity of the cement. The cements consisted of bisphenol-a-glycidyl methacrylate-based (Bis-GMA based) monomers as an organic matrix, with a bioactive filler of apatite/wollastonite containing glass-ceramic (AW-GC) or sintered hydroxyapatite (HA) or beta-tricalcium phosphate (beta-TCP) powder. Each filler was mixed with the monomers in proportions of 50, 70, and 80% (w/w), giving a total of nine cement subgroups. The nine subgroups were designated AWC50, AWC70, AWC80, HAC50, HAC70, HAC80, TCPC50, TCPC70, and TCPC80. The compressive and bending strengths of AWC were found to be higher than those of HAC and TCPC for all bioactive filler contents. We also evaluated the cements in vivo by packing them into the intramedullary canals of rat tibiae. To compare the osteoconductivity of the cements, an affinity index was calculated for each cement; it equaled the length of bone in direct apposition to the cement, expressed as a percentage of the total length of the cement surface. Microradiographic examination up to 26 weeks after implantation revealed that AWC showed a higher affinity index than HAC and TCPC for each filler content although the affinity indices of all nine subgroups (especially the AWC and HAC subgroups) increased with time. New bone had formed along the AWC surface within 4 weeks, even in the cement containing AW-GC filler at only 50% (w/w); observation of the cement-bone interfaces using a scanning electron microscope showed that all the cements had directly contacted the bone. At 4 weeks the AWC had bonded to the bone via a 10 micron-thick reactive layer; the width of the layer, in which partly degraded AW-GC particles were seen, became slightly thicker with time. On the other hand, in the HAC- and TCPC-implanted tibiae, some particles on the cement surface were surrounded by new bone and partly absorbed or degraded. The results suggest that the stronger bonding between the inorganic filler and the organic matrix in the AWC cements gave them better mechanical properties. The results also indicate that the higher osteoconductivity of AWC was caused by the higher reactivity of the AW-GC powder on the cement surface.

Animals↗

PubMed1999

Study of the relationship between sticky human serum IgA1 and its O-glycan glycoform.

The high-affinity IgA1 toward jacalin was mostly composed of aggregated IgA1 and abundantly contained the asialo disaccharide, Galbeta1,3GalNAc, in the O-linked oligosaccharide in the hinge region [Journal of Biochemistry 120, 92-97 (1996)]. Meanwhile, the removal of sialic acid from IgA1 accelerated the aggregation of the IgA1 molecule [J. Am. Soc. Nephrol. 9, 2048-2054 (1998)]. In order to examine the nature of such a sticky IgA1, affinity chromatography using asialo-IgA1 (deSIgA1)-Sepharose was carried out. Seventeen percent of normal human serum IgA1, 27% of asialo-IgA1 (IgA1-S), and 48% of asialo-, agalacto-IgA1 (IgA1-SG) were bound to the column. Removal of the N-acetylgalactosamine residue from IgA1-SG resulted in a decreasing affinity toward deSIgA1-Sepharose. Thus, the binding ability toward the column was the highest for the IgA1-SG among the deglycosylated IgA1s. On the other hand, heat treatment of IgA1 accelerated the aggregation but decreased its binding ability toward the column. Such heat denaturation probably destroys the structure of the binding site. Since the enzymatic removal of the N-glycan sugar chains did not induce the aggregation and exhibited no effect on the binding, the incomplete O-linked sugar chain on the hinge portion should be directly related to the sticky characteristics of the IgA1 molecule. The binding was non-covalent and not strong because the asialo-, agalacto-hinge glycopeptide was eluted slightly slower than the native one from the column and the bound IgA1 was dissociated in the presence of 1 M NaCl.

Chromatography, Affinity↗

PubMed1999

The cDNA cloning of human placental ecto-ATP diphosphohydrolases I and II.

The cDNA clones of two isoforms (enzymes I and II) of human placental ecto-ATP diphosphohydrolases have been isolated based on the N-terminal amino acid (aa) sequence of the immunopurified 82 kDa protein and characterized. The cDNA clone encoding enzyme I consists of 2081 nucleotides and the predicted enzyme I consists of 517 aa residues. Enzyme I has a 5'-UTR and an N-terminal 11 aa sequence that differ from CD39, but the rest of the sequence is the same as CD39. The hydropathy plot indicated that enzyme I has two hydrophobic regions near the N- and C-termini of the molecule. In contrast, enzyme II consists of 1814 nucleotides and the predicted protein consists of 306 aa residues. The sequence of 1-1018 nucleotides of enzyme II is identical to that of enzyme I, but the 1019-1814 nucleotide sequence is different from both enzyme I and CD39. The hydropathy plot indicated that enzyme II has one hydrophobic region near the N-terminus, suggesting that enzyme II is also anchored to the cell membrane. It is, however, likely that some of enzyme II exists as a soluble form in plasma, possibly after proteolytic processing.

Adenosine Triphosphatases↗

PubMed1999

Transmission electron microscopic study of interface between bioactive bone cement and bone: comparison of apatite and wollastonite containing glass-ceramic filler with hydroxyapatite and beta-tricalcium phosphate fillers.

We developed a bioactive bone cement that consists of apatite and wollastonite containing glass-ceramic (AW-GC) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) based resin. In this study, we made three types of cement (designated AWC, HAC, and TCPC) consisting of either AW-GC, hydroxyapatite (HA), or beta-tricalcium phosphate (beta-TCP) powder as the inorganic filler and Bis-GMA based resin as the organic matrix. These cements were implanted into rat tibiae and cured in situ. Specimens were prepared 1, 2, 4, and 8 weeks after the operation and observed using transmission electron microscopy. Each of the bone cements was in direct contact with the bone. In AWC-implanted tibiae, the uncured surface layer of Bis-GMA based resin was completely filled with newly formed bone-like tissue 2 weeks after implantation. The AW-GC particles were surrounded by bone and were in contact with bone through an apatite layer. No intervening soft tissue was seen. In HAC-implanted tibiae, it took 4 weeks for the uncured layer to completely fill with newly formed bonelike tissue. The HA particles were also in contact with bone through an apatite layer. In TCPC-implanted tibiae, it took 8 weeks for the uncured layer to fill with newly formed bone-like tissue. The new bone that formed on the TCPC was not as dense as that on the AWC or HAC, and an intervening apatite layer was not evident. Results indicated that AWC had higher bioactivity than either HAC or TCPC.

Animals↗

PubMed1999

Mutual separation of hinge-glycopeptide isomers bearing five N-acetylgalactosamine residues from normal human serum immunoglobulin A1 by capillary electrophoresis.

Immunoglobulin A1 (IgA1) from normal human serum is known to have O-linked sugar chains, sialylated Galbeta1,3GalNAc, in the hinge portion. In order to reduce the microheterogenity of the sugar chain, the hinge glycopeptide prepared from IgA1 was sequentially treated with neuraminidase and beta-galactosidase. The asialo-, agalacto-hinge glycopeptide (HGP-SG) composed of a 33-mer peptide (HP33) and N-acetylgalactosamine (GalNAc) residues was obtained. The HGP-SG was separated into three major peaks, A, B and C, by high-performance liquid chromatography (HPLC). Each glycopeptide fraction was further separated by capillary electrophoresis (CE). Peaks A, B and C with HPLC abundantly contained HP33 bearing five and six N-acetylgalactosamine residues (HGP33-5,6GN), HGP33-4,5GN and HGP33-3,4GN, respectively. Among these glycopeptide peaks, only the HGP33-5GN peak was partly split into two peaks based on the CE analysis - HGP33-5GN-alpha and -beta. The glycopeptide, HGP25-5GN shortened by the thermolysin digest of HGP33-SG was also well separated into the alpha and beta forms by CE analysis. No differences in their mass and peptide portion were observed between HGP25-5GN-alpha and -beta. Therefore, the obtained result might indicate that HGP25-5GN-alpha was an isomer of HGP25-5GN-beta differing in its stereospecific structure of the peptide portion and/or the attachment site of the GalNAc residue.

Acetylgalactosamine↗

PubMed1999

Matrix metalloproteinases and lysosomal cysteine proteases in osteoclasts contribute to bone resorption through distinct modes of action.

The effects of inhibitors of matrix metalloproteinases (MMPs) and lysosomal cysteine proteases on osteoclastic pit formation in dentine slices were investigated. A nonspecific cysteine protease inhibitor, E-64, inhibited pit formation on naked slices in a concentration-dependent manner, and at 10 microM E-64 reduced the pit volume by 70%. However, up to 10 microM of the MMP inhibitor, BB-94, did not show any inhibition of pit formation. On the other hand, on slices coated with reconstituted basement membrane, both BB-94 and E-64 at 10 microM showed a marked decrease in pit volume by 73% and 68%, respectively. By a combination of treatment with both BB-94 and E-64, pit formation could be completely suppressed. These results suggest that MMPs are necessary for the migration of precursor and/or immature osteoclasts to bone surface through basement membranes, while cysteine proteases are essential for the osteoclastic degradation of bone collagen.

Animals↗

PubMed1999

Aggregated human serum immunoglobulin A1 induced by neuraminidase treatment had a lower number of O-linked sugar chains on the hinge portion.

A part of human serum immunoglobulin A1(IgA1) was aggregated by treatment with neuraminidase. Aggregated IgA1 was separated from non-aggregated IgA1 by gel permeation chromatography. The prepared asialo-hinge glycopeptide (asialo-HGP) from both IgA1 subfractions was treated with beta-galactosidase to determine the number of beta-linked sugar chains attached on the hinge region. Removal of the galactose residue from asialo-HGP resulted in the HPLC separation of three major peaks. MALDI-TOFMS analysis of the glycopeptides also indicated the presence of three HGP components with three, four and five N-acetylgalactosamine (GalNAc) residues, respectively. Comparison of their relative content among the glycopeptide components showed a higher content of the HGP component with a lower number of GalNAc residues on aggregated IgA1. Thus, asialo-HGP prepared from aggregated IgA1 induced by neuraminidase treatment had an incomplete core structure of O-linked oligosaccharides. Especially, the result suggested that the reduced number of the attached O-linked oligosaccharides on IgA1 take part in phenomena such as self-aggregation of asialo-IgA1.

Amino Acid Sequence↗

PubMed1999

Osteoconductivity and bone-bonding strength of high- and low-viscous bioactive bone cements.

A study was conducted to evaluate the osteoconductivity and bone-bonding ability of two types of bioactive bone cement, both consisting of apatite and wollastonite containing glass-ceramic powder (AW-P), fused silica glass powder (SG-P), submicron fumed silica as an inorganic filler, and bisphenol-a-glycidyl methacrylate (Bis-GMA) based resin as an organic matrix. The cements had two kinds of formulas: one (dough-type cement; designated DTC) composed of 85% (w/w) filler and 15% resin, which was developed for fixation of the acetabular component in total hip arthroplasty and could be handled manually; and one (injection-type cement; designated ITC) composed of 79% (w/w) filler and 21% resin. ITC was developed for fixation of the femoral component and, because it had a lower viscosity than DTC, could be injected. The DTC and ITC both contained 73% AW-P, 25% SG-P, and 2% fumed silica in the weight ratio of the filler component. Two other types of cement, both of which consisted of 83.3% AW-P or SG-P, 1.7% fumed silica, and 15% resin, were used as reference material (designated AWC or SGC) for a detaching test. Following the packing of bone defects in the rat tibiae with either DTC or ITC, histological examination revealed that the DTC and ITC had both directly contacted the bone and were almost completely surrounded by bone by 16 weeks after the surgery and that no marked biodegradation had occurred at 52 weeks postimplantation. Rectangular plates (2 x 10 x 15 mm) of AWC, DTC, ITC, and SGC were implanted into the metaphysis of the tibia of male rabbits and the failure load was measured by a detaching test at 10 and 25 weeks after implantation. The failure loads of AWC, DTC, ITC, and SGC were 3.65, 2.21, 2.44, and 0.04 kgf at 10 weeks and 4.87, 2. 81, 2.82, and 0.13 kgf at 25 weeks, respectively. Observation of the bone-implant interface by scanning electron microscopy and energy dispersive X-ray microanalysis revealed that all the samples except SGC formed direct contact with the bone and that only AWC-implanted tibiae had a layer of a low calcium and phosphorus level at the bone-implant interface. Results showed that DTC and ITC have excellent osteoconductivity and bone-bonding ability under non-weight-bearing conditions.

Animals↗

PubMed1999

Enhancement of bone-bonding strengths of titanium alloy implants by alkali and heat treatments.

The purpose of this study is to evaluate the bone-bonding ability of alkali- and heat-treated titanium alloys. Smoothed-surface rectangular plates of Ti6Al4V, Ti6Al2Nb1Ta, and Ti15Mo5Zr3Al were prepared. The plates were inserted transcortically into the proximal metaphyses of bilateral rabbit tibiae, with alkali- and heat-treated plates inserted on the right side, and untreated plates on the left. The tensile failure loads between the implants and the bones were measured after 8, 16, and 24 weeks by a detaching test. The untreated implants showed almost no bonding even at 16 weeks, and only weak bonding at 24 weeks. In contrast, treated implants showed bonding to bone at all time periods. Histological examination showed that alkali- and heat-treated alloys bonded directly to the bone. Conversely, the untreated implants had an intervening layer of fibrous tissue between the bone and the plate, or only partial direct contact with the bone. This study demonstrates that alkali and heat treatments enhance the bone-bonding strength of these titanium alloys. Although in this study even tentative conditions of the treatments enhance the bonding strength of the titanium alloys, further work is required to determine the optimum conditions for treatment to give the highest bonding strength. These new bioactive titanium alloys are available for weight-bearing and bone-bonding orthopedic devices.

Alkalies↗

PubMed1999

Graded surface structure of bioactive titanium prepared by chemical treatment.

An NaOH treatment of pure titanium (Ti) forms a sodium titanate hydrogel surface layer with a smooth graded interface structure to the Ti metal substrate. Subsequent heat treatment at 600 degrees C of the NaOH-treated Ti forms an amorphous sodium titanate surface layer with a smooth graded interface structure similar to the Ti metal substrate. These treated Ti metals both form an apatite surface layer with a smooth graded interface structure to the Ti metal substrates in simulated body fluid (SBF). The smooth graded interface structures give a tight bond of the apatite layer to the substrates. Heat treatment at 800 degrees C of the NaOH-treated Ti forms crystalline sodium titanate and a rutile surface layer with a graded interface structure to the Ti metal substrate, which is intervened by a thick titanium oxide. This substrate forms an apatite layer with a graded interface structure to the Ti metal substrate, which is intervened by a thick titanium oxide in SBF. This irregular graded structure gives a less tight bond of the apatite layer to the substrate.

Apatites↗

PubMed1999

Composition and structure of the apatite formed on PET substrates in SBF modified with various ionic activity products.

An apatite layer was formed on polyethyleneterephthalate (PET) substrates by the following biomimetic process. PET substrates were placed on granular particles of a CaO-SiO2-based glass in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma to form apatite nuclei on their surfaces (first treatment). They then were soaked in modified SBFs, the ion concentrations of which were changed to give a variation in ionic activity product of apatite (IP), in order to make the apatite nuclei grow (second treatment). The Ca/P atomic ratio and the lattice constant c of the formed apatite decreased from 1.54 to 1.40 and from 6.880 to 6.838 A, respectively, with increasing ion concentrations from 0.75 to 2.00 times those of SBF, that is, with increasing IP from 10(-96.6) to 10(-91.9). This was attributed to an increase in the concentration of HPO4(2-) ion substituting for the PO4(3-) ion sites, which gave an increase in the Ca2+ in the apatite. Even the apatite formed in 1.00 SBF showed a Ca/P ratio of 1.51 and lattice constants a of 9.432 A and c of 6.870 A. The Ca/P ratio and lattice constant c were smaller and the lattice constant a was larger than those of the bone apatite; its Ca/P ratio and its lattice constants a and c, were 1.65, 9.419 A, and 6.88 A, respectively. This was attributed to the lower content (2.64 wt%) of the CO3(2-) ion substituting for the PO4(3-) ion sites of the apatite compared to that of the bone apatite (5.80 wt%). The lower content of the CO3(2-) ion in the apatite might be caused by the lower concentration of HCO3- ion in 1.00 SBF compared to that in human blood plasma.

Apatites↗

PubMed1999

Bone-bonding behavior of alumina bead composite.

Previously we developed an alumina bead composite (ABC) consisting of alumina bead powder (AL-P) and bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based resin and reported its excellent osteoconductivity in rat tibiae. In the present study, are evaluated histologically and mechanically the effect of alumina crystallinity on the osteoconductivity and bone-bonding strength of the composite. AL-P was manufactured by fusing crushed alpha-alumina powder and quenching it. The AL-P was composed mainly of amorphous and delta-crystal phases of alumina. Its average particle size was 3.5 microm, and it took a spherical form. Another composite (alpha ALC), filled with pure alpha-alumina powder (alpha AL-P), was used as a referential material. The proportion of powder added to each composite was 70% w/w. Mechanical testing of ABC and alpha ALC indicated that they would be strong enough for use under weight-bearing conditions. The affinity indices for ABC, determined using male Wistar rat tibiae, were significantly higher than those for alpha ALC (p < 0.0001) up to 8 weeks. Composite plates (15 x 10 x 2 mm) that had an uncured surface layer on one side were made in situ in a rectangular mold. One of the plates was implanted into the proximal metaphysis of the tibia of a male Japanese white rabbit, and the failure load was measured by a detaching test 10 weeks after implantation. The failure loads for ABC on its uncured surface [1.91+/-1.23 kgf (n = 8)] were significantly higher than those for alpha ALC on its uncured surface [0.35+/-0.33 kgf (n = 8); (p < 0.0001)], and they also were significantly higher than those for ABC on the other (cured surface) side (p < 0.0001). Histological examinations using rabbit tibiae revealed bone ingrowth into the composite only on the uncured surface of ABC. This study revealed that the amorphous phase of alumina and formation of an uncured surface layer are needed for the osteoconductive and bone-bonding ability of ABC. ABC shows promise as a basis for the development of a highly osteoconductive and mechanically strong biomaterial.

Aluminum Oxide↗

PubMed1999

In vitro analysis of the stimulation of bone formation by highly bioactive apatite- and wollastonite-containing glass-ceramic: released calcium ions promote osteogenic differentiation in osteoblastic ROS17/2.8 cells.

We analyzed the mechanisms of the efficient bone formation on the osteoconductive surface of apatite- and wollastonite-containing glass-ceramic (AW) by using an in vitro system. AW releases Ca ions and bonds to bone via a submicron-thick hydroxycarbonate apatite (HCA) layer. AW disks were conditioned with simulated body fluid (SBF) to grow HCA layers, and the amount of released Ca ion was regulated by modulating the conditioning time from 24 to 240 h. Surface-transformed AW disks increased alkaline phosphatase (AP) activity in osteoblastic ROS17/2.8 cells by 1.5- to threefold over unconditioned disks. AW disks conditioned for 24 h [AW(24)], which had a homogeneous, submicron-thick apatite layer and increased extracellular ionized Ca concentration ([Ca(2+)](e)) in the culture medium to the greatest extent, enhanced the AP activity the most. High [Ca(2+)](e) promoted osteogenic differentiation in ROS17/2.8 cells: It increased AP activity in a dose-dependent manner by up to 1.6-fold, and up-regulated the expression of AP, osteocalcin (OC), and transforming growth factor-beta1 mRNAs in dose- and time-dependent manners. AW(24) enhanced AP activity in ROS17/2.8 cells as much as AW disks conditioned with SBF containing serum to exhibit in vivo surface-structure changes. AW(24) increased AP activity in ROS17/2.8 cells by 1.6-fold and enhanced the expression of AP and OC mRNAs significantly, compared with sintered hydroxyapatite (HA). After implantation of AW and HA in the distal metaphyses of rabbit femurs, thin, newly formed bone lined with cuboidal, osteoblast-like cells was characteristically observed adjacent to the AW surface within 8 days. These results provide evidence for the hypothesis that AW stimulates bone formation on its surface by increasing [Ca(2+)](e) to promote the HCA layer formation and the differentiation of osteogenic cells.

Animals↗

PubMed1999

Sol-gel modification of silicone to induce apatite-forming ability.

Silicones formed with silanol groups on their surfaces were prepared by partial hydrolysis and polycondensation of tetraethoxysilane (TEOS) dispersed in silicones in molecular scale. Although the silanol-modified silicones thus prepared formed no apatite in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma within 21 d, they formed a bone-like apatite layer in situ on their surfaces in a solution (1.5 SBF) with ion concentrations 1.5 times the SBF within 7 d. This indicates that the silanol groups formed on the silicones by the present method can induce the apatite nucleation in 1.5 SBF and hence, apatite-coated silicones can be fabricated by a biomimetic process. Apatite-silicone composites thus prepared could exhibit mechanical properties analogous to the natural bone as well as bioactivity.

Apatites↗

PubMed1999

Bonelike apatite coating on organic polymers: novel nucleation process using sodium silicate solution.

A bonelike apatite layer was formed on organic polymers when sodium silicate was used as a catalyst for the apatite nucleation, and modified simulated body fluid was used as a medium for the apatite growth. The apatite-forming ability was the highest when the SiO2 concentration and SiO2/Na2O mole ratio of the sodium silicate solution were above 2.0 M and 1.0-1.5, respectively. It is assumed that particular silicate oligomers with structures such as dimer, linear trimer and cyclic tetramer contribute to the apatite nucleation the most. The apatite layer was formed not only on limited surfaces but also on the whole surfaces of fine PET fibers constituting a fabric. This method is expected to enable the bonelike apatite coating on various kinds of materials with complex shapes.

Apatites↗

PubMed1999

The effect of heat treatment on bone-bonding ability of alkali-treated titanium.

The purpose of this study was to evaluate the bone-bonding ability of alkali-treated titanium with and without heat treatment. Three groups of smooth titanium plate were prepared: control, or pure titanium, alkali-treated titanium, and alkali- and heat-treated titanium. The plates were inserted transcortically into the proximal metaphyses of bilateral rabbit tibiae. The tensile failure loads between implants and bones were measured at two time intervals using a detaching test. The tensile failure loads of the alkali- and heat-treated titanium group were 2.71 and 4.13 kgf, at 8 and 16 weeks, respectively, and significantly higher than those of the other titanium groups. Histological examination revealed that alkali- and heat-treated titanium was in direct contact with bone, but the other titanium groups had a thin intervening fibrous tissue. This result indicated that the alkali-treated titanium without heat treatment had no bone-bonding ability due to the unstable reactive surface layer of alkali-treated titanium. In conclusion, both alkali and heat treatment are essential for preparing bioactive titanium and this bioactive titanium is thought to be useful for orthopedic implants with cementless fixation.

Alkalies↗

PubMed1999

Apatite formation on PDMS-modified CaO-SiO2-TiO2 hybrids prepared by sol-gel process.

Dense and homogeneous monolithics of polydimethylsiloxane (PDMS)-modified CaO-SiO2-TiO2 hybrids were successfully synthesized by sol-gel process. They were assumed to be composed of a silica and titania network incorporated with PDMS and the calcium ion ionically bonded to the network. Among them, the hybrids containing relatively larger amounts of the calcium in their surfaces formed an apatite on their surfaces within only 1 or 0.5 day in a simulated body fluid with ion concentrations nearly equal to those of human flood plasma. This indicates that they are highly bioactive. Organic-inorganic hybrids synthesized by a sol-gel process usually exhibit high ductility, low elastic modulus and high mechanical strength. The present hybrids are, therefore, expected to be useful as a new kind of bone-repairing material, because of their high bioactivity and unique mechanical properties.

Apatites↗

PubMed1999

Conformational studies on the specific cleavage site of Type I collagen (alpha-1) fragment (157-192) by cathepsins K and L by proton NMR spectroscopy.

Cathepsins K and L are cysteine proteinases which are considered to play an important role in bone resorption. Type I collagen is the most abundant component of the extracellular matrix of bone and regarded as an endogenous substrate for the cysteine proteinases in osteoclastic bone resorption. We have synthesized a fragment of Type I collagen (alpha-1) (157-192) as a substrate for the cathepsins and found that cathepsins K and L cleave the fragment at different specific sites. The major cleavage sites for cathepsin K were Met159-Gly160, Ser162-Gly163 and Arg165-Gly166, while those for cathepsin L were Gly166-Leu167 and Gln180-Gly181. The structure of the fragment was analyzed in aqueous solution by circular dichroism and proton NMR spectroscopy and the difference in the molecular recognition of collagen by cathepsins K and L was discussed from the structural aspect.

Amino Acid Sequence↗