Enzymatic degradation of Antheraea pernyi silk fibroin 3D scaffolds and fibers

In this study, the in vitro enzymatic degradation behavior of the regenerated Antheraea pernyi silk fibroin (Ap-SF) three-dimensional (3D) scaffolds and the natural Ap-SF fibers exposed to enzyme solutions of α-chymotrypsin, collagenase IA and protease XIV were investigated. The results indicated that all three proteases could degrade the Ap-SF 3D scaffolds, and the degradation ability was in the order protease XIV>collagenase IA>α-chymotrypsin. The regenerated Ap-SF 3D scaffold could be degraded completely in 18 days when exposed to 1.0 U/ml protease XIV at 37°C, whereas under the same condition, the natural Ap-SF fiber only lost 5.6% of its weight, revealing its long-term degradation characteristics. There were abundant peptides and some free amino acids in the Ap-SF degradation products, but no free alanine. We suggested that the polyalanine block in the regenerated Ap-SF 3D scaffolds had strong resistance to enzyme attack. The proteolytic attack occurred in the non-polyalanine block of Ap-SF. The degradation rate of Ap-SF materials depended on the molecular conformation of Ap-SF, which could be controlled in the manufacturing process.     

Degradation of a signal peptide by protease IV and oligopeptidase A.

The degradation of the prolipoprotein signal peptide in vitro by membranes, cytoplasmic fraction, and two purified major signal peptide peptidases from Escherichia coli was followed by reverse-phase liquid chromatography (RPLC). The cytoplasmic fraction hydrolyzed the signal peptide completely into amino acids. In contrast, many peptide fragments accumulated as final products during the cleavage by a membrane fraction. Most of the peptides were similar to the peptides formed during the cleavage of the signal peptide by the purified membrane-bound signal peptide peptidase, protease IV. Peptide fragments generated during the cleavage of the signal peptide by protease IV and a cytoplasmic enzyme, oligopeptidase A, were identified from their amino acid compositions, their retention times during RPLC, and knowledge of the amino acid sequence of the signal peptide. Both enzymes were endopeptidases, as neither dipeptides nor free amino acids were formed during the cleavage reactions. Protease IV cleaved the signal peptide predominantly in the hydrophobic segment (residues 7 to 14). Protease IV required substrates with hydrophobic amino acids at the primary and the adjacent substrate-binding sites, with a minimum of three amino acids on either side of the scissile bond. Oligopeptidase A cleaved peptides (minimally five residues) that had either alanine or glycine at the P'1 (primary binding site) or at the P1 (preceding P'1) site of the substrate. These results support the hypothesis that protease IV is the major signal peptide peptidase in membranes that initiates the degradation of the signal peptide by making endoproteolytic cuts; oligopeptidase A and other cytoplasmic enzymes further degrade the partially degraded portions of the signal peptide that may be diffused or transported back into the cytoplasm from the membranes.     

The subcellular distribution of peptides immunoreactive for the amino-terminal of pro-cholecystokinin in rat brain

Antiserum 1942 raised against the synthetic peptide V-9-M is specific for the amino-terminus of pro-cholecystokinin (pro-CCK). It detects three major peptides in whole rat brain extracts with molecular weights of about 13 000 (peak 1), 8000 (peak 2) and 2700 (peak 3), of which the major one is peak 3. Rat brain was found to contain large quantities of these V-9-M-like peptides. Subcellular fractionation of whole rat brain was performed to determine what cellular component was enriched in these peptides. The molecular weight of the V-9-M-like and CCK-8-like peptides enriched in various subcellular fractions has been determined by Sephadex G-50 chromatography. Primary subcellular fractionation experiments indicated a significant enrichment of V-9-M-like peptides in the mitochondrial pellet (P2), a lesser amount in the microsomal pellet (P3), and a slight enrichment in the soluble fraction (S3). Further purification of the P2 fraction demonstrated an increase of V-9-M-like immunoreactivity in purified synaptosomes. With the exception of the enrichment in the soluble fraction, V-9-M-like peptides follow a similar distribution to that of CCK-8-like peptides. Sephadex chromatography of P2 and P3 fractions indicates that the major form of V-9-M present is the peak 3 (2700) form. This V-9-M-like peptide may represent an intermediate in the processing of CCK, and its presence in synaptosomes may indicate that the proteolytic cleavage of pro-CCK into CCK 58 and peak 3 takes place in synaptic vesicles.     

Enzymatic, alkaline, and autocatalytic degradation of poly(L-lactic acid): effects of biaxial orientation

The hydrolytic degradation of biaxially oriented and de-oriented (melt-crystallized) poly(l-lactic acid) (PLLA) films was investigated in Tris-HCl-buffered solution (pH 8.6) with proteinase K, alkaline solution, and phosphate-buffered solution (pH 7.4) by the use of gravimetry, gel permeation chromatography, differential scanning calorimetry, and scanning electron microscopy. Biaxial orientation disturbed the proteinase K-catalyzed enzymatic degradation of PLLA films and the effects of biaxial orientation overcame those of crystallinity. The former may be due to the fact the enzyme cannot attach to the extended (strained) chains in the amorphous regions of the biaxially oriented PLLA film or cannot catalyze the cleavage of the strained chains. Another probable cause is that the enzyme can act only at the film surface of the biaxially oriented PLLA film, in marked contrast with the case of the de-oriented PLLA films where enzymatic degradation can proceed beneath the spherulitic crystalline residues. The effects of biaxial orientation on the alkaline and autocatalytic degradation of the PLLA films were insignificant for the periods studied here. The crystallinity rather than the biaxial orientation seems to determine the alkaline and autocatalytic degradation rates of the PLLA films. The accumulation of crystalline residues formed as a result of selective cleavage and removal of the amorphous chains was observed for the de-oriented PLLA films, but not for the biaxially oriented PLLA film, when degraded in the presence of proteinase K. This means the facile release of formed crystalline residues from the surface of the biaxially oriented PLLA film during enzymatic degradation, due to the fact that the crystalline regions of the biaxially oriented PLLA film were oriented with their c axis parallel to the film surface.     

Purification of human erythrocyte proteolytic enzyme responsible for degradation of oxidant-damaged hemoglobin. Evidence for identifying as a member of the multicatalytic proteinase family

Exposure of human red cells to oxidants such as phenylhydrazine, 2,4-dimethylphenylhydrazine and 4-hydrazinobenzoic acid stimulates the proteolysis of hemoglobin as evidenced by the increase in the rate of the free alanine and acid soluble amino groups released. An enzyme responsible for proteolytic degradation of oxidized hemoglobin, was purified from cytosolic fraction of erythrocytes by a DEAE-batch procedure followed by gel-filtration and ion-exchange chromatography. The final enzyme preparation produces a single band in non-denaturing polyacrylamide gel electrophoresis, and eight different bands of 23-32 kDa when subjected to polyacrylamide gel electrophoresis under denaturing conditions. The native enzyme has a molecular mass of about 700 kDa as estimated by gel filtration. The enzyme, unable to hydrolyze native hemoglobin, cleaves phenylhydrazine-treated hemoglobin into small peptides without free amino acid release. In addition, the enzyme shows an endopeptidase activity towards synthetic peptides having a tyrosine or an arginine in the P1 position, whereas it does not hydrolyze shorter peptides and those with a proline in the P1 or P2 position. The proteolytic activity of the enzyme against oxidized hemoglobin is inhibited by chymostatin and p-chloromercuribenzoate, while it is stimulated by N-ethylmaleimide and epoxysuccinylleucylamido-(4-guanidino)butane (E-64). The peptidase activity assayed on succinyl-Leu-Leu-Val-Tyr-MCA is inhibited by chymostatin, hemin, N-ethylmaleimide and p-chloromercuribenzoate. The results obtained show that in human erythrocytes oxidized hemoglobin is cleaved into peptides by a high molecular mass proteinase identified as a member of the multicatalytic proteinase family. It is also suggested that the complete degradation of oxidized hemoglobin to free amino acids requires the involvement of a further proteolytic enzyme(s) which remain(s) to be identified.     

Soluble enkephalin-degrading enzymes released by lymphomic and erythroleukaemic cell lines

The possible existence of soluble proteolytic enzymes released by cells of lymphomic (U937 and 1301) and erythroleukaemic (K562) lines was studied measuring the hydrolysis of³H-leucine enkephalin in the presence of cell-free supernatants obtained from these lines. Results indicate that leu-enkephalin is rapidly degraded in the presence of these supernatants, and that enkephalin disappearance is paralleled by the formation of peptides that can be interpreted as its hydrolysis fragments. To characterize the factors involved in leu-enkephalin degradation, cell supernatants were analyzed by ion exchange and by steric exclusion chromatography. Data obtained indicate the presence of three groups of proteins active in leu-enkephalin degradation: aminopeptidases, dypeptidylaminopeptidases and dypeptidylcarboxypeptidases. In all three lines, these enzymes are represented by a considerable number of distinct activities. The sizable number of soluble enzymes identified and the signficant total activity observed suggest a possible role in the regulatory degradation of informational peptides, as proposed by several groups for the membrane-bound proteolytic enzymes of immunocompetent cells.     

聚3-羟基丁酸酯（PHB）生物降解过程的研究

利用DS9701菌株对聚3-羟基丁酸酯(PHB)膜进行降解,对降解到不同程度的PHB膜采用扫描电子显微镜观察其表面形态结构的变化,并对其降解产物进行分析测定.结果表明,PHB的生物降解首先发生在PHB表面的非晶部分,随后结晶部分开始降解,并且降解首先发生在球晶的中心部分.DS9701菌株所产生的PHB解聚酶主要降解PHB的第二个酯键,降解产物为二聚体.     

Stabilization of basic fibroblast growth factor with dextran sulfate.

Dextran sulfate protected bFGF from heat and acid inactivation and from proteolytic degradation. The protective effect was stronger than that of heparin which is known as a stabilizer of bFGF. Dextran sulfate and bFGF formed a high molecular weight complex via ionic interaction when mixed together in aqueous solution. The complex was dissociated when the ionic strength was increased and the protective effect was completely abolished. Successive digestion of bFGF with Staphylococcus aureus V8 protease and pepsin followed by affinity chromatography on an immobilized dextran sulfate column and reversed-phase high performance liquid chromatography yielded three positively charged fragment peptides, Tyr24-Phe30, Tyr106-Trp114 and Tyr124-Leu138. These results suggest that dextran sulfate stabilizes bFGF by binding close to the putative heparin binding sites of the bFGF molecule.     

Mechanism of pneumococcal cell wall degradation in vitro and in vivo.

We compared the products of autolytic amidase-catalyzed wall degradation in vivo (in penicillin-induced lysis) and in vitro. Pneumococci labeled in their cell wall stem peptides by radioactive lysine were treated with penicillin, and the nature of wall degradation products released to the medium during lysis of the bacteria was determined. At early times of lysis (20% loss of wall label), virtually all the radioactive peptides released (greater than 94%) were of high molecular size and were still attached to glycan and teichoic acid. At times of more extensive bacterial lysis (56%), progressively larger and larger fractions of the released peptides became free, i.e., detached from glycan and teichoic acid. Analysis of the nondegraded residual wall material by high-resolution high-pressure liquid chromatography revealed that this in vivo-triggered autolysis did not involve selective hydrolysis of some of the chemically distinct stem peptides. Parallel in vitro experiments yielded completely different results. Purified pneumococcal cell walls labeled with radioactive lysine were treated in vitro with low concentrations of pure amidase, and the nature of wall degradation products released during limited hydrolysis and after more extensive degradation was determined. In sharp contrast to the in vivo experiments, the main products of in vitro hydrolysis were free peptides. After a short treatment with amidase (resulting in a 20% loss of label), the material released was enriched for the monomeric stem peptides. At all times of hydrolysis (including the time of extensive degradation), only a relatively small fraction of the released wall peptides was covalently attached to glycan and teichoic acid components (17% as compared with 40% in the intact cell wall). We propose that the in vivo-triggered amidase activity first attacks the amide bonds in some strategically located (or unprotected) stem peptides that hold large segments of cell wall material together. The observations indicate that the in vivo activity of the pneumococcal autolysin is under topographic constraints.     

Degradation of ornithine decarboxylase in reticulocyte lysate is ATP-dependent but ubiquitin-independent

Reticulocyte lysate contains all the components of the ubiquitin-dependent proteolytic system. Several proteins are degraded in reticulocyte lysate in a ubiquitin-dependent manner. However, none of the proteins studied has a short intracellular half-life. We have investigated the degradation of ornithine decarboxylase (ODC), one of the most labile proteins in mammalian cells. ODC is efficiently degraded in reticulocyte lysate depleted of the ubiquitin activating enzyme, E1, in fraction II of reticulocyte lysate completely lacking ubiquitin, and in fraction II depleted of the entire complex of enzymes responsible for the ligation of ubiquitin to target proteins. The degradation of ODC is ATP dependent. Therefore, our results demonstrate that in addition to the ubiquitin-dependent proteolytic pathway, reticulocyte lysate contains at least one additional ATP-dependent proteolytic pathway. In vitro synthesized ODC served as a substrate in the present degradation study. Its successful utilization establishes a general strategy for investigating the degradation of short-lived proteins (for which a corresponding cDNA is available), that constitute a very small fraction of cellular proteins and for which purification is difficult or impossible. In contrast to ODC synthesized in vitro, that isolated from cells was not degraded by the reticulocyte lysate degradation system, suggesting that post-translational modifications may be involved in regulating ODC degradation.     

Conformational stability of type I collagen triple helix: evidence for temporary and local relaxation of the protein conformation using a proteolytic probe

Native collagen polypeptides exist in a unique triple helical conformation resistant to most proteinases. In this study, the stability of type I collagen triple helix, employing a mixture of trypsin and alpha-chymotrypsin as a proteolytic probe, was examined. The degradation of type I [3H]collagen was monitored as 3H-labeled peptides soluble in trichloroacetic acid (TCA) or by sodium dodecyl sulfate (SDS)-polyacrylamide slab gel electrophoresis. In one set of experiments, collagen substrates were preincubated at various temperatures for up to 8 h, followed by a 15-min proteolytic treatment at the same temperature. At 43 degrees C, most of the collagen was degraded, while the fraction of the substrate degraded at 40, 38, and 35 degrees C was 53, 41 and 19%, respectively. This fraction was independent of the preincubation time which varied from 10 to 480 min. Thus, at any given temperature, a constant fraction of the collagen substrate was susceptible to proteolysis. Measurement of the midpoint temperature (Tm) of the helix to coil transformation for type I collagen, at neutral pH employing an increasing temperature gradient and brief proteolysis at the individual temperatures, indicated a value of 38.8 degrees C. However, determination of the Tm by employing proteolytic digestions at a constant temperature (30 degrees C) using conditions under which the nonhelical peptides are readily digested to TCA-soluble peptides while native collagen resists such proteolysis, indicated a value of 42.7 degrees C. In further studies, collagen was subjected to continuous proteolysis for up to 24 h. A large fraction of collagen was digested at 30 or 34 degrees C, temperatures well below the Tm of the helix to coil transformation. SDS-polyacrylamide gel electrophoresis of the degradation products obtained at these temperatures revealed multiple cleavage fragments. Finally, temperature double-jump experiments indicated that the destabilization of the triple helix is reversible provided that the Tm of the substrate is not exceeded. The results provide evidence for reversible and local relaxation of the collagen triple helix.     

猪胰脏中胰岛素拮抗肽的分离纯化及其性质的初步研究

从猪胰脏的酸醇提取液中纯化了一个新的活性多肽——胰岛素拮抗肽,它在整体和细胞水平上对胰岛素都有明显的拮抗作用。猪胰脏的酸醇提取液经CM-52、BioGel P-6、DEAE-52及RP-HPLC纯化后,可得到纯的胰岛素拮抗肽。它能剂量相关地抑制胰岛素在离体大鼠脂肪细胞中的促脂合成活性,抑制50％胰岛素活性时所需的胰岛素拮抗肽为2.0×10~(-10)mol/L与被拮抗的胰岛素剂量在同一水平上。该肽含有较多的碱性氨基酸,分子量的3 000,其N-末端是封闭的。胰岛素拮抗肽的上述理化特征及其对胰岛素的拮抗活性均不同于目前已知的胰脏活性多肽。它对脂肪细胞中胰岛素的拮抗作用可能具有重要的生理意义。     

Acid Soluble Peptides in Rat Skeletal Muscle

The acid soluble peptide fraction was prepared from rat skeletal muscle, and the amino acid composition of the fraction was analyzed. The peptide fraction was rich in glutamic acid (or glutamine) and glycine and was poor in branched chain or aromatic amino acids. Since the peptide fraction contained N^τ-methylhistidine, the fraction or at least a part of it was presumed to be composed of intermediate peptides of protein degradation in skeletal muscle. At least 31 spots were detected in the fraction by one dimensional paper electrophoresis.     

Glial Fibrillary Acidic Protein in the Cytoskeletal and Soluble Protein Fractions of the Developing Rat Brain

The distribution of glial fibrillary acidic protein (GFAP) into cytoskeletal and soluble protein fractions during development of the rat brain has been studied by quantitative immunoblotting and enzyme-linked immunosorbent assay (ELISA). These assays indicate that cytoskeletal GFAP accounts for nearly all the total GFAP in the adult rat brain, and that the developmental increase in the GFAP content of the rat brain is due to accumulation of GFAP into the cytoskeleton. A small and constant amount of the total GFAP was detected in the soluble protein fraction. This GFAP had an apparent molecular mass (Mr) similar to that of the highest Mr form of GFAP detected in the cytoskeletal fraction. In contrast to the assays for cytoskeletal GFAP, no significant increase in the GFAP concentration of the soluble protein fraction could be measured during development. Sensitive, calibrated immunoblotting of cytoskeletal and soluble protein with [125I]protein A confirmed these findings, and showed that both cytoskeletal and soluble GFAP are first detected during the same period of foetal rat brain development. A finite and reproducible amount of lower Mr forms of GFAP were observed in the cytoskeletal fraction even when prepared in the presence of stringent proteolytic inhibitors. These presumed proteolytic degradation products of GFAP increased in abundance during development, parallel to the increase in cytoskeletal GFAP content of the rat brain. However, the abundant proteolytic degradation products of GFAP found in the cytoskeletal fraction were not detected in the soluble protein fraction at any age studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kallikrein activation of a high molecular weight atrial peptide

Mammalian atrial extracts contain bioactive peptides that exert profound effects upon renal function and isolated smooth muscle preparations. Gel filtration chromatography of rat atrial extract separates the activity into two peaks having apparent molecular weights of 20,000 to 30,000 and less than 10,000. Mild proteolytic treatment (trypsin 1 U/ml) of the high molecular weight fraction enhances the smooth muscle relaxant activity of this fraction and concomitantly reduces the apparent molecular weight of this fraction to less than 10,000. In this report we show that urinary and submaxillary kallikrein enhances the activity of rat atrial extracts in a similar fashion. Pretreatment of the high molecular weight fraction with either kallikrein (1 microgram/ml) enhances the smooth muscle relaxant activity of this fraction. Similar treatment of the low molecular weight fraction had no effect. The enhancement of the bioactivity of the high molecular weight substance(s) by the kallikreins was abolished by aprotinin but was unaffected by soybean trypsin inhibitor. These results suggest that exogenous addition of tissue kallikrein activates a high molecular weight peptide by limited proteolysis. Analysis of the kallikrein-treated high molecular weight peptide fraction by gel filtration indicates that the biological activity comigrates with the low molecular weight peptides present in the original atrial extract.     

Proteins of the lupin family, binding molybdenum, tungsten, and radionuclide effluents from the Chernobyl Atomic Energy Station

Yellow lupine seeds were found to contain two proteins and a low molecular weight fraction possessing the ability to bind Mo, W and radionuclides from the Chernobyl nuclear power in vivo and the 185W isotope in vitro. These proteins differ in their electrophoretic mobility. The electrophoretically less mobile protein undergoes proteolytic degradation; the proteolytic product retains the ability to accumulate microelements.     

Analysis of soluble fibrin complexes by agarose gel chromatography and protamine sulfate gelation.

The molecular makeup of soluble fibrin complexes was studied by gel exclusion chromatography using radio-labelling to characterize individual components in protein mixtures. Products of limited plasmin degradation of fibrinogen and mixtures of fibrinogen and "early" fibrinogen digests formed high molecular weight soluble fibrin complexes upon incubation with thrombin. Purified, nonclottable fragment Y did not incorporate into soluble fibrin complexes, nor could we demonstrate incorporation of fragments D and E as previously described from our laboratory. Thus, under the conditions of these experiments, soluble fibrin complexes have two identifiable components, fibrin monomer and clottable fragment X monomer, although incorporation of native fibrinogen or fragment X unreacted by thrombin into soluble fibrin complexes cannot be excluded. Individual fractions of thrombin-treated early fibrinogen digests isolated by agarose gel chromatography were treated with protamine sulfate at 37 degrees C resulting in precipitation-gelation of greater than 90 per cent of high molecular weight soluble fibrin complexes; whereas, less than 10 per cent of lower molecular weight fibrinogen degradation products precipitated by protamine sulfate. These findings do not support the widely held concept that soluble fibrin complexes incorporate nonclottable degradation products of fibrinogen proteolysis, nor do they support the notion that the so-called paracoagulation reaction induced by protamine sulfate results from the splitting of complexes between fibrin monomer and nonclottable fibrinogen degradation products.     

Low density lipoprotein degradation by secretory granules of rat mast cells. Sequential degradation of apolipoprotein B by granule chymase and carboxypeptidase A

The secretory granules of rat serosal mast cells are able efficiently to degrade the apolipoprotein B component of low density lipoproteins (LDL) Kokkonen, J. O., and Kovanen, P. T. (1985) J. Biol. Chem. 260, 14756-14763). The granules are known to contain two neutral proteases with complementary specificities: a chymotrypsin-like endopeptidase called chymase, and an exopeptidase, the granule carboxypeptidase A. The role of this enzyme pair in the proteolytic degradation of LDL was studied with the aid of specific enzyme inhibitors. Incubation of LDL with intact granules (both enzymes active) led to the formation of numerous low molecular weight peptides and the liberation of free amino acids, most of which (95%) were aromatic (Phe, Tyr, Trp) or branched-chain aliphatic (Leu, Ile, Val). Selective inhibition of granule carboxypeptidase A (leaving chymase active) blocked the liberation of free amino acids, but left the formation of peptides uninhibited. On the other hand, selective inhibition of granule chymase (leaving carboxypeptidase A active) totally abolished the proteolytic degradation of LDL. The results are consistent with a model according to which the proteolytic degradation of LDL by mast cell granules results from coordinated action of the two granule-bound enzymes, whereby the chymase first cleaves peptides from the apolipoprotein B of LDL, and thereafter the carboxypeptidase A cleaves amino acids from the peptides formed.     

Insight into the bovine milk peptide LPcin‐YK3 selection in the proteolytic system of Lactobacillus species

Antimicrobial peptides are class of small, positively charged peptides known for their broad‐spectrum antimicrobial activity. Antimicrobial activities for most antimicrobial peptides have largely remained elusive, particularly in the lactic acid bacteria. However, recently our investigation using LPcin‐YK3, an antimicrobial peptide from bovine milk, suggests that in vitro antimicrobial activity was reduced over 100‐fold compared with pathogenic bacteria. Additionally, for the structural study of how antimicrobial peptide undergoes its reaction at the proteolytic pathway of lactic acid bacteria based on degradation assay and propidium iodide staining, we performed molecular docking for interaction between oligopeptide‐binding protein A and LPcin‐YK3 peptide. Given that degradation related to the LPcin‐YK3 peptide in lactic acid bacteria proteolytic system, the inhibitory inactivity of LPcin‐YK3 against beneficial lactic acid bacteria strains may be one of the primary pharmacological properties of recombinant peptide discovered in bovine milk. These results provide structural and functional insights into the proteolytic mechanism and possibility as a putative substrate of oligopeptide‐binding protein A in respect of LPcin‐YK3 peptide.     

Crystallization behavior and environmental biodegradability of the blend films of poly(3-hydroxybutyric acid) with chitin and chitosan

Crystallization behavior and environmental biodegradability were investigated for the films of bacterial poly(3-hydroxybutyric acid) (PHB) blends with chitin and chitosan. The blend films showed X-ray diffractive peaks that arose from the PHB crystalline component. It was suggested that the lamellar thickness of the PHB crystalline component in the blends was large enough to show detectable X-ray diffractive peaks, but this was too small to show observable melting endotherm in the DSC thermogram and the crystalline band absorption in the FT-IR spectrum. In the PHB/chitin and PHB/chitosan blends, thermal transition temperatures of PHB amorphous region observed by dynamic mechanical thermal analysis were almost the same as that of neat PHB. Both the PHB/chitin and the PHB/chitosan blend films biodegraded in an environmental medium. Several blend films showed faster biodegradation than the pure-state component polymers.