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PubMed1999

Studies of the reactivity of artificial peroxidase-like hemoproteins based on antibodies elicited against a specifically designed ortho-carboxy substituted tetraarylporphyrin.

The temperature and pH dependence as well as the selectivity of the peroxidase activity of a complex associating a monoclonal antibody 13G10 with its iron(III)-alpha,alpha,alpha,beta-mesotetrakis(ortho-carboxyphenyl) porphyrin (Fe(ToCPP)) hapten have been studied and compared to those of Fe(ToCPP) alone. It first appears that the peroxidase activity of the 13G10-Fe(ToCPP) complex is remarkably thermostable and remains about 5 times higher than that of Fe(ToCPP) alone until at least 80 degrees C. Secondly, this complex is able to use not only H2O2 as oxidant but also a wide range of hydroperoxides such as alkyl, aralkyl and fatty acid hydroperoxides and catalyze their reduction 2-6-fold faster than Fe(ToCPP) alone. It is also able to catalyze the oxidation by H202 of a variety of reducing cosubstrates such as 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), o-phenylenediamine (OPD), 3,3',5,5'-tetramethylbenzidine (TMB) and 3,3'-dimethoxybenzidine 3-8-fold faster than Fe(ToCPP) alone, the bicyclic aromatic ABTS and TMB being the best reducing cosubstrates. Finally, a pH dependence study, between pH 4.6 and 7.5, of the oxidation of ABTS by H2O2 in the presence of either 13G10-Fe(ToCPP) or Fe(ToCPP) shows that Km(H2O2) values vary very similarly for both catalysts, whereas very different variations are found for the k(cat) values. With Fe(ToCPP) as catalyst the k(cat) value remains constant around 100 min(-1) whereas with the 13G10-Fe(ToCPP) complex, it increases sharply below pH 5 to reach 540 min -1 at pH 4.6. This could be due to the participation of a carboxylic acid side chain of the antibody protein, as a general acid-base catalyst, to the heterolytic cleavage of the O-O bond of H2O2 leading to the highly reactive iron(V)-oxo intermediate in the peroxidase mechanism. Accordingly, the modification of the carboxylic acid residues of antibody 13G10 by glycinamide leads to a 50% decrease of the peroxidase activity of the 13G10-Fe(ToCPP) complex.

Antibodies↗
PubMed1999

Does diphenylene iodonium chloride have any effect on the O2- -generating step of plant peroxidases?

The O2*- -generating step of plant peroxidases during their catalytic cycle is represented by the decay of compound III (CoIII) into ferriperoxidase, which most likely involves the dissociation of a ferric-O2*- complex to yield the ferric form of the enzyme and O2*-. Diphenylene iodonium chloride (DPI), at 50-100 microM, does not significantly enhance the stability of CoIII of peroxidase, as judged by the values of k(decay), and therefore, DPI appears to have no effect on the O2*- -generating step of plant peroxidases. From these results, it is concluded that caution should be exercised when considering peroxidase as a possible enzyme target of O2*- -mediated plant physiological processes sensitive to DPI inhibition.

Electrophoresis, Polyacrylamide Gel↗
PubMed2001

Oxidation of cinnamyl alcohols and aldehydes by a basic peroxidase from lignifying Zinnia elegans hypocotyls.

The xylem of 26-day old Zinnia elegans hypocotyls synthesizes lignins derived from coniferyl alcohol and sinapyl alcohol with a G/S ratio of 43/57 in the aryl-glycerol-beta-aryl ether core, as revealed by thioacidolysis. Thioacidolysis of Z. elegans lignins also reveals the presence of coniferyl aldehyde end groups linked by beta-0-4 bonds. Both coniferyl and sinapyl alcohols, as well as coniferyl and sinapyl aldehyde, are substrates of a xylem cell wall-located strongly basic peroxidase, which is capable of oxidizing them in the absence and in the presence of hydrogen peroxide. This peroxidase shows a particular affinity for cinnamyl aldehydes with kappa(M) values in the mu(M) range, and some specificity for syringyl-type phenols. The affinity of this strongly basic peroxidase for cinnamyl alcohols and aldehydes is similar to that shown by the preceding enzymes in the lignin biosynthetic pathway (microsomal 5-hydroxylases and cinnamyl alcohol dehydrogenase), which also use cinnamyl alcohols and aldehydes as substrates, indicating that the one-way highway of construction of the lignin macromolecule has no metabolic "potholes" in which the lignin building blocks might accumulate. This fact suggests a high degree of metabolic plasticity for this basic peroxidase, which has been widely conserved during the evolution of vascular plants, making it one of the driving forces in the evolution of plant lignin heterogeneity.

Aldehydes↗
PubMed2002

Polysaccharide degradation by Fenton reaction--or peroxidase-generated hydroxyl radicals in isolated plant cell walls.

The formation of hydroxyl radicals (OH*) by peroxidase was confirmed by EPR spectroscopy using ethanol/alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone as a spin-trapping system specific of OH*. The effect of OH*, generated either non-enzymatically with the Fenton reaction (H(2)O(2) + Fe(2+)) or with horseradish peroxidase in the presence of O(2) and NADH, on cell walls isolated from maize (Zea mays) coleoptiles or soybean (Glycine max) hypocotyls was investigated. OH* produced by these reactions attack polysaccharides in the wall, demonstrated by the release of a heterogeneous mixture of polymeric breakdown products into the incubation medium. The peroxidase-catalyzed degradation of cell-wall polysaccharides can be inhibited by KCN and superoxide radical (O(2)*) or OH* scavengers. These data support the hypothesis that OH*, produced by cell-wall peroxidases in vivo, act as wall-loosening agents in plant extension growth.

Cell Wall↗
PubMed1977

Cytochemical localization of peroxidase activity in normal, proliferating and neoplastic thyroid tissues of rats. An ultrastructural study.

In the control animals of thyroid peroxidase is localized within the membrane of rough endoplasmic reticulum, perinuclear cisternae, microvilli, lamellar structures of the GOLGI apparatus and dispersed through the cytoplasm small vesicles. 3 weeks treatment of the animals with MTU leads to disappearance of the peroxidase activity from the follicular cells. However, a prolongation of MTU administration until the 6th month and latter causes a reappearance of the peroxidase activity within the same structures of the proliferating cells as in the control animals. In the epithelial cells of follicular and papillary carcinomas the reaction product is observed predominantly within the membrane of the rough endoplasmic reticulum, perinuclear space and outher membrane of the microvilli. The changes in the inhibitory effect of MTU on the peroxidase activity during thyroid carcinogenesis are discussed.

Animals↗
PubMed1997

Peroxidase activity in shoot apical meristem from Spinacia.

Peroxidase activity was localized in the shoot apical meristem (SAM) of Spinacia at the light and electron microscope level with the histochemical method employing H2O2 and 3,3'-diaminobenzidine. At the light microscopic level, peroxidase activity was examined in unfixed cryostat sections at different pHs. The enzyme was found to be more intense at low than at neutral and high pH. The activity was evenly distributed over the different regions of the meristem at low pH, whereas it was more intense in the rib meristem at pH 6.8 and 7.2. At the ultrastructural level, peroxidase activity was found at 3 cellular sites: the cell wall, the tonoplast and the plasmalemma. These results were discussed in relationship with the in situ distribution of peroxidases in plant cells and other enzymes in vegetative SAM.

3,3'-Diaminobenzidine↗
PubMedDate not supplied

Placental peroxidase--further purification of the enzyme and oxidation of thiobenzamide.

Human term placental peroxidase [donor: hydrogen peroxide (H2O2) oxidoreductase] from non-smoking women was purified by extraction of the membrane fraction with 0.5 M Ca2+ followed by affinity chromatography on concanavalin A, hydrophobic chromatography on phenyl sepharose CL-4B and gel filtration chromatography on sephacryl S-200 columns. The final enzyme preparation was 110-fold pure when compared to the Ca2+ extract and the overall recovery of the procedure was 55 per cent. SDS-PAGE of the final product showed the presence of four protein staining bands of molecular weights 30, 32.5, 35 and 55 KDa. The purified peroxidase eluted as a single peak from the sephacryl S-200 column suggesting apparent homogeneity of the protein. The purified placental peroxidase oxidized thiobenzamide to its sulfoxide. The highest rate of TB S-oxidation under optimum conditions was 18 +/- 2.15 mumoles/min/mg protein. The H2O2-dependent thiobenzamide S-oxidation catalysed by the placental peroxidase was inhibited by KCN and NaN3 with IC50 values of 16.9 and 34 microM respectively.

Chromatography, Affinity↗
PubMed2002

Mesopone cytochrome c peroxidase: functional model of heme oxygenated oxidases.

The effect of heme ring oxygenation on enzyme structure and function has been examined in a reconstituted cytochrome c peroxidase. Oxochlorin derivatives were formed by OsO(4) treatment of mesoporphyrin followed by acid-catalyzed pinacol rearrangement. The northern oxochlorin isomers were isolated by chromatography, and the regio-isomers assignments determined by 2D COSY and NOE 1H NMR. The major isomer, 4-mesoporphyrinone (Mp), was metallated with FeCl(2) and reconstituted into cytochrome c peroxidase (CcP) forming a hybrid green protein, MpCcP. The heme-altered enzyme has 99% wild-type peroxidase activity with cytochrome c. EPR spectroscopy of MpCcP intermediate compound I verifies the formation of the Trp(191) radical similar to wild-type CcP in the reaction cycle. Peroxidase activity with small molecules is varied: guaiacol turnover increases approximately five-fold while that with ferrocyanide is approximately 85% of native. The electron-withdrawing oxo-substitutents on the cofactor cause a approximately 60-mV increase in Fe(III)/Fe(II) reduction potential. The present investigation represents the first structural characterization of an oxochlorin protein with X-ray intensity data collected to 1.70 A. Although a mixture of R- and S-mesopone isomers of the FeMP cofactor was used during heme incorporation into the apo-protein, only the S-isomer is found in the crystallized protein.

Cloning, Molecular↗
PubMed1998

A method of combining biocytin tract-tracing with avidin-biotin-peroxidase complex immunocytochemistry for pre-embedding electron microscopic labeling in neonatal tissue.

A new method that allows the combination of avidin-biotin-peroxidase visualization of antigens and silver-intensified gold labeling of biocytin, a rapid tract-tracer, is described. The method provides a practical tool for in vivo and in vitro studies of chemically specified afferent-target relationships and particularly in developing neural pathways where biocytin is invaluable as a rapidly transporting, sensitive tracer requiring little permeabilizing agents. Transported biocytin was first visualized with silver-intensified colloidal gold conjugated to anti-biotin IgG. This was followed by blocking of all unbound biotin groups of biocytin in the tissue with an Avidin-Biotin blocking kit. Finally, a second antigen, neuronal nitric oxide synthase NOS or GluR2/3 subunit of AMPA receptors, was visualized selectively with avidin-biotin-peroxidase/DAB. This protocol allowed visualization of two chromagens that could be distinguished by electron microscopy. The presence of biocytin was evident by silver particles, while accumulation of peroxidase reaction product marked only the antibody labeling: no cross-reaction between biocytin and the avidin-biotin-peroxidase was observed.

Animals↗
PubMed2001

Molecular characterisation of mitochondrial and cytosolic trypanothione-dependent tryparedoxin peroxidases in Trypanosoma brucei.

In trypanosomatids, removal of hydrogen peroxide and other aryl and alkyl peroxides is achieved by the NADPH-dependent trypanothione peroxidase system, whose components are trypanothione reductase (TRYR), trypanothione, tryparedoxin (TRYX) and tryparedoxin peroxidase (TRYP). Here, we report the cloning of a multi-copy tryparedoxin peroxidase gene (TRYP1) from Trypanosoma brucei brucei encoding a protein with two catalytic VCP motifs similar to the cytosolic TRYP from Crithidia fasciculata. In addition, we characterise a novel single copy gene encoding a second tryparedoxin peroxidase (TRYP2). TRYP2 shows 51% similarity to TRYP1, possesses a putative mitochondrial import sequence at its N-terminus and has a variant IPC motif replacing the second VCP motif implicated in catalysis in other 2-Cys peroxiredoxins. TRYP1 and TRYP2 were expressed in Escherichia coli, and the purified recombinant proteins shown to utilise hydrogen peroxide in the presence of NADPH, trypanothione, TRYR and TRYX from T. brucei, similar to the C. fasciculata cytoplasmic system. Western blots showed that TRYX, TRYP1 and TRYP2 are expressed in both bloodstream and procyclic forms of the life cycle. To determine the precise localisation of TRYX, TRYP1 and TRYP2 in the parasite, polyclonal antibodies to purified recombinant TRYX and TRYP1 and monoclonal antibody to TRYP2 were generated in mice. In-situ immunofluorescence and immunoelectron microscopy revealed a colocalisation of TRYX and TRYP1 in the cytosol, whereas TRYP2 was principally localised in the mitochondrion.

Amino Acid Sequence↗
PubMed1996

Molecular characterization of the glutathione peroxidase gene of the human malaria parasite Plasmodium falciparum.

In this paper we report the isolation and the characterization of a gene encoding the antioxidant enzyme glutathione peroxidase from the human malaria parasite Plasmodium falciparum. This gene contains two introns of 208 and 168 bp and is present in a single copy on chromosome 13. The open reading frame encodes a protein with a predicted length of 205 amino acids, which possesses a potential cleavage site between residues 21 and 22 after a hydrophobic region with the characteristics of a signal sequence. Therefore, the mature protein is predicted to be 184 residues long with a molecular mass of 21404 Da. In comparison with other known glutathione peroxidases many amino acid residues implicated in catalysis are conserved in the malarial enzyme. Phylogenetic analysis indicates that the deduced protein sequence is more closely related to plant glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase. A 1.5-kb transcript was identified in asynchronous erythrocytic stages.

Amino Acid Sequence↗
PubMed2002

Reaction of hydrogen peroxide and peroxidase activity in carboxymethylated cytochrome c: spectroscopic and kinetic studies.

The peroxidase activity of carboxymethylated cytochrome c (Cmcytc) has been investigated by spectroscopic and kinetic techniques to examine the effect of carboxymethylation on the peroxidase activity of native cytochrome c (cytc). The optical spectrum suggests that the reaction of Cmcytc with H(2)O(2) proceeds through only one intermediate, compound I. The apparent rate constant (k(app)) for the reaction was found to be 17, 72 and 210 M(-1) s(-1) at pH 7.0, 5.0 and 3.5 respectively. These values are about 60 times larger than those reported for native cytc (0.236 M(-1) s(-1) at pH 7.0), and about five orders of magnitude lower than those for classical peroxidases. Cmcytc was found to catalyse oxidation of organic and inorganic substrates. The second order rate constant for the oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) by Cmcytc (205 [H(2)O(2)] s(-1)) is found to be larger than the corresponding value for native cytc (50 [H(2)O(2)] s(-1)) at pH 6.0. The carboxymethylation of cytc ruptures the Fe-S (Met 80) bond and increases the rate of its reaction with H(2)O(2), and its catalytic activity. The specific activity of Cmcytc was measured spectrophotometrically by the reported method using ABTS as substrate, and was found to be 288, 473 and 872 microM min(-1) mg(-1) at pH 7.0, 5.0 and 3.5 respectively. Resonance Raman studies indicated the presence of a bis-histidine coordinated form of Cmcytc at neutral pH, and the existence of a population distribution of different ligation states such as bis-histidine (HH), histidine-water (HW) and five coordinate (5C) forms at lower pH. The relative population of different species in Cmcytc was found to be HH (approximately 100%, approximately 50%, approximately 44%), HW (approximately 0%, approximately 44%, 41%) and 5C (approximately 0%, approximately 6%, 15%) at pH 7.0, 4.7 and 3.1 respectively. We have attempted to correlate the pH dependence of the reaction of Cmcytc with hydrogen peroxide and its peroxidase activity with the haem stereochemical structures observed for Cmcytc. Steady-state and time-resolved tryptophan fluorescence studies on Cmcytc were done to probe the conformational changes around the haem pocket of Cmcytc.

Animals↗
PubMed1999

The electron paramagnetic resonance characterisation of a copper-containing extracellular peroxidase from Thermomonospora fusca BD25.

The actinomycete Thermomonospora fusca BD25 contains a peroxidase with a high activity over a broad range of temperature and pH and a high stability against denaturing agents. Unusually this peroxidase (PO) is a non-haem enzyme. As prepared PO is characterised by two electron paramagnetic resonance (EPR) signals, detected at liquid helium temperature, a free radical signal (g=2.0045) and a broad signal at g=2.056. The peroxidase activity of the purified enzyme was assayed using H(2)O(2) and 2,4-dichlorophenol (DCP). The intensity of the free radical EPR signal correlated with the peroxidase activity in a variety of enzyme preparations. Furthermore, when DCP and H(2)O(2) were added to PO a significant increase of both the free radical signal and the broad signal at g=2.056 was observed. We associate the increase of the broad signal with the oxidation of the preparation since a similar increase can be achieved by the addition of ferricyanide. The high intensity of the broad signal in the ferricyanide treated PO allowed us to deconvolute the signal into several components using the difference in their relaxation characteristics: two distinct copper signals were detected, one of which was similar to a type 2 centre. Furthermore a symmetrical singlet was detected at g=2.059, consistent with the presence of an iron complex with a high degree of symmetry and weakly coordinated ligands.

Actinomycetales↗
PubMed2000

Different fungal manganese-oxidizing peroxidases: a comparison between Bjerkandera sp. and Phanerochaete chrysosporium.

Two manganese-oxidizing peroxidases differing in glycosylation degree were purified from fermenter cultures of Bjerkandera sp. They were characterized and compared with the three manganese-oxidizing peroxidase isoenzymes obtained from the well-known ligninolytic fungus Phanerochaete chrysosporium. All the enzymes showed similar molecular masses but those from P. chrysosporium had less acidic isoelectric point. Moreover, the latter strictly required Mn2+ to oxidize phenolic substrates whereas the Bjerkandera peroxidases had both Mn-mediated and Mn-independent activity on phenolic and non-phenolic aromatic substrates. Taking into account these results, and those reported for Bjerkandera adusta and different Pleurotus species, we concluded that two different types of Mn(2+)-oxidizing peroxidases are secreted by ligninolytic fungi.

Amino Acid Sequence↗
PubMed2000

Nucleotide sequence analysis, overexpression in Escherichia coli and kinetic characterization of Anacystis nidulans catalase-peroxidase.

Bifunctional catalase-peroxidases are the least understood type of peroxidases. A high-level expression in Escherichia coli of a fully active recombinant form of a catalase-peroxidase (KatG) from the cyanobacterium Anacystis nidulans (Synechococcus PCC 6301) is reported. Since both physical and kinetic characterization revealed its identity with the wild-type protein, the large quantities of recombinant KatG allowed the examination of both the spectral characteristics and the reactivity of its redox intermediates by using the multi-mixing stopped-flow technique. The homodimeric acidic protein (pI = 4.6) contained high catalase activity (apparent K(m) = 4.8 mM and apparent k(cat) = 8850 s(-1)). Cyanide is shown to be an effective inhibitor of the catalase reaction. The second-order rate constant for cyanide binding to the ferric protein is (6.9 +/- 0.2) x 10(5) M(-1 )s(-1) at pH 7.0 and 15 degrees C and the dissociation constant of the cyanide complex is 17 microM. Because of the overwhelming catalase activity, peroxoacetic acid has been used for compound I formation. The apparent second-order rate constant for formation of compound I from the ferric enzyme and peroxoacetic acid is (1.3 +/- 0.3) x 10(4 )M(-1 )s(-1) at pH 7.0 and 15 degrees C. The spectrum of compound I is characterized by about 40% hypochromicity, a Soret region at 406 nm, and isosbestic points between the native enzyme and compound I at 355 and 428 nm. Rate constants for reduction of KatG compound I by o-dianisidine, pyrogallol, aniline and isoniazid are shown to be (7.3 +/- 0.4) x 10(6) M(-1 )s(-1), (5.4 +/- 0.3) x 10(5) M(-1 )s(-1), (1.6 +/- 0.3) x 10(5) M(-1 )s(-1) and (4.3 +/- 0.2) x 10(4) M(-1 )s(-1), respectively. The redox intermediate formed upon reduction of compound I did not exhibit the classical red-shifted peroxidase compound II spectrum which characterizes the presence of a ferryl oxygen species. Its spectral features indicate that the single oxidizing equivalent in KatG compound II is contained on an amino acid which is not electronically coupled to the heme.

Amino Acid Sequence↗
PubMed2003

Characterisation of maize peroxidases having differential patterns of mRNA accumulation in relation to lignifying tissues.

Among other enzymes, peroxidases have been proposed to participate in the latest steps of lignin biosynthesis. In order to identify new proteins involved in such mechanism of lignification in maize, we have isolated three cDNAs coding for three different peroxidases, named ZmPox1, ZmPox2, and ZmPox3, respectively. Computational analyses of these three proteins correlate with features typically attributed to heme-containing plant peroxidases of approximately 300 amino acid residues. Although with different expression levels, ZmPox2 and ZmPox3 mRNAs are accumulated in the elongating region of young roots but not in the root tips. In addition, the ZmPox2 mRNA levels are up-regulated by wounding and ethylene treatments. However, ZmPox1 is also expressed in the root tip meristems, where lignification does not occur. Finally, in situ hybridisations indicate that ZmPox2 mRNA localises in vascular tissues and epidermis. Although ZmPox1 mRNA localises in the same regions as ZmPox2 mRNA in root tips, its mRNA is only detected in the epidermis but not in the vascular tissues of young roots, suggesting that the function of ZmPox1 is not correlated to lignification. In addition, although ZmPox3 mRNA is also detected in the regions where lignification occurs, the involvement of this peroxidase in such a mechanism remains to be further investigated due to its very low expression level. Therefore, based on its amino acid sequence and mRNA accumulation and localisation patterns, the involvement of ZmPox2 in the latest steps of lignification is discussed.

Amino Acid Sequence↗
PubMed2000

Purification of soybean peroxidase (Glycine max) by metal affinity partitioning in aqueous two-phase systems.

Combining two concepts in downstream processing, this work investigates the partitioning of a crude soybean peroxidase (Glycine max) in an aqueous two-phase system by metal affinity. A liquid-liquid extraction process using metal ligands was developed in two steps with the aim of purifying the enzyme peroxidase. PEG 4000 was activated using thionyl chloride, covalently linked to iminodiacetic acid (IDA), and the specific metal ligand Cu2+ was attached to the PEG 4000-IDA. In the first step, the system was composed of 14% (w/w) PEG 4000-IDA-Cu2+ and 8% (w/w) Na2SO4, and the peroxidase partitioned mainly to the top phase (K = 24). In the second step, a system formed by 14% PEG 4000 and 10% phosphate was used to revert the value of the partition coefficient of peroxidase to the bottom salt-rich phase (K = 0.05), thereby achieving a recovery of 64% of the purified enzyme.

Chromatography, Affinity↗
PubMed1998

Sea urchin ovoperoxidase: oocyte-specific member of a heme-dependent peroxidase superfamily that functions in the block to polyspermy.

Ovoperoxidase is one of several oocyte-specific proteins that are stored within sea urchin cortical granules, released during the cortical reaction, and incorporated into the newly formed fertilization envelope. Ovoperoxidase plays a particularly important role in this process, crosslinking the envelope into a hardened matrix that is insensitive to biochemical and mechanical challenges and thus providing a permanent block to polyspermy. Here we present the primary structures of two ovoperoxidases as predicted from cDNAs cloned from the sea urchins Strongylocentrotus purpuratus (AF035380) and Lytechinus variegatus (AF035381). We also present a proposed scheme for the post-translational processing of ovoperoxidase based upon comparisons between the cDNA and protein structures and taking into account previously published reports. The sea urchin ovoperoxidase sequences conform to a profile shared by members of a heme-dependent animal peroxidase family, including the mammalian myelo-, lacto-, eosinophil, and thyroid peroxidases. Using in situ RNA hybridizations, we showed that the mRNA of S. purpuratus ovoperoxidase (4 kb) is present exclusively in oocytes, and is turned over rapidly following germinal vesicle breakdown. Taking into account our immunoblot and N-terminal sequencing data along with reports from similar peroxidases, we propose that ovoperoxidases are synthesized in a pre-pro form and proteolytically processed to result in the 70 and 50 kDa forms that are found in the fertilization envelope. The sequence and structural data presented here will facilitate our continuing studies of the biogenesis of cortical granules and the fertilization envelope. Additionally, since ovoperoxidase activities have been reported in a wide range of animals, these cDNAs will be useful in uncovering similar peroxidases used in the fertilization reactions of other metazoan eggs.

Amino Acid Sequence↗