Sperm Motility Regulatory Proteins: A Tool to Enhance Sperm Quality

Sperm forward motility is an essential parameter in mammalian fertilization. Studies from our laboratory have identified and characterized a few unique sperm motility regulatory proteins/glycoproteins from the male reproductive fluids and mammalian blood serum. The purified sperm motility-initiating protein (MIP) from caprine epididymal plasma as well as the forward motility-stimulating factor (FMSF) and motility-stimulating protein (MSP) from buffalo and goat serum, respectively, have high efficacy to initiate or increase motility in nonmotile or less motile sperm. Antibody of sperm motility inhibitory factor (MIF-II) has the high potential to enhance sperm vertical velocity and forward motility by increasing intracellular cyclic adenosine monophosphate (cAMP) level. The appearance and disappearance of D-galactose–specific lectin and its receptor along the epididymis has been reported to be involved in motility regulation in spermatozoa. A novel synthetic cryopreservation method and role of lipid to protect membrane damage during cryopreservation have been demonstrated. Motility-promoting proteins may be extremely useful for improving cattle breeding and breeding of endangered species, thereby helping in enhanced production of animal products as well as in the conservation of animals. Isolated proteins and developed cryopreservation technology may also be beneficial in human infertility clinics to increase the chance of fertilization

Synthesis, Characterization, and Structure of Mixed-Ligand Cobalt (II) Complex with N, O Donor Sites

A mononuclear octahedral mixed-ligand cobalt (II) complex [Co(H2L)(PhCOO)2] (1) has been prepared by using H2L (N,N′-dimethyl-N,N′-bi(2-hydroxy-3,5-di methyl benzyl)-ethylenediamine) as a facially coordinating tetradentate ligand with a N2O2 donor center along with sodium benzoate as an ancillary ligand. Complex 1 has been characterized by a single-crystal X-ray diffraction study, as well as by other spectroscopic tools. The complex crystallizes in the monoclinic space group C2 with a = 31.73(3) Å, b = 7.868(3) Å, c = 19.131(15) Å, and β = 125.25(3)°. The single-crystal X-ray diffraction study shows that in the mononuclear cobalt (II) complex [Co(H2L)(PhCOO)2] (1), the metal center adopts an octahedral environment

Synthesis, Structure and Catechol Oxidase Activity of Mono Nuclear Cu(II) Complex with Phenol-Based Chelating Agent with N, N, O Donor Sites

A square-planar Cu(II) complex [Cu(L)Cl], 1, with sterically constrained tridentate phenol-based ligand (HL= N,N,N′-trimethyl-N′-(2-hydroxy-3,5-di-tert-butylbenzyl)-ethylenediamine) with N, N, O donor sites has been synthesized. The complex is characterized by single crystal X-ray diffraction study as well as other spectroscopic techniques. The reported complex crystallizes in monoclinic space group C2/c with a = 30.248(6), b = 13.750(3) and c = 11.410(2) Å with β = 110.232(2)°. The Cu(II) ion adopts a square planar environment in this complex. Electrochemical study of the complex 1 gives quasi-reversible reductive response at E1/2 ≈ −0.5 V due to the reduction of the Cu(II) center along with a reversible oxidation peak at E1/2 ≈ 0.75 V. The oxidation peak arises due to the ligand-based oxidation of phenolate group to phenoxyl radical in the complex. The Cu(II) complex exhibits catechol oxidase activity in methanol as observed by the UV–vis spectroscopy of the aerial oxidation of 3,5-DTBC to 3,5-DTBQ and the reaction proceeds via the formation of ligand phenoxyl radical. The turnover number for complex 1 is 2560 h−1

Tetra-, Tri-, and Mononuclear Manganese(II/III) Complexes of a Phenol-Based N2O2 Capping Ligand: Use of Carboxylates as Ancillary Ligands in Tuning the Nuclearity of the Complexes

Manganese(II/III) complexes of a phenol-based tetradentate ligand L2- [H2L ) N,N′-dimethyl-N,N′-bis(2-hydroxy- 3,5-dimethylbenzyl)-ethylenediamine], namely, [Mn4(L)2(PhCOO)6] (1), [Mn3(L)2(CH3CH2COO)2(OMe)2] · H2O (2), and [Mn(L){(CH3)3CCOO}(CH3OH)] · CH3OH (3), have been synthesized. The basicity and steric congestion provided by the carboxylate moiety used as an ancillary ligand have profound influence on tuning the nuclearity of these compounds. Results of X-ray crystallography, electronic spectroscopy, and variable-temperature (1.8-300 K) magnetic measurements have been used to characterize these compounds. Complex 1 has a very interesting centrosymmetric structure that involves two crystallographically equivalent binuclear [MnII-MnIII] units, connected together by a pair of syn-anti bridging benzoates to generate a “dimer of dimers” structural motif. Compound 2 with propionate as the ancillary ligand, on the other hand, has a nearly linear MnIII-MnII-MnIII core with antiferromagnetically coupled (J ) -0.13 cm-1) metal centers. Compound 1 has an ST ) 9 spin ground state with ferromagneticlly coupled metal centers (Jwb) 2.8(1) and Jbb ) 0.09(2) cm-1) that failed to function as a single molecule magnet due to the presence of low-lying excited states with smaller spin values and a weak magnetic anisotropy. The electron paramagnetic resonance spectrum of 1 in the frozen solution (12 K) displays two signals in the g ) 2 and g ) 4 regions, each split into six lines due to 55Mn (I ) 5/2) superhyperfine couplings. The use of bulky pivalate as a replacement for benzoate provides enough steric bulk to generate a mononuclear species [Mn(L){(CH3)3CCOO}(CH3OH)] · CH3OH (3). The lone manganese(III) center in this compound has an octahedral geometry, completed by the tetradentate ligand L2- together with an axially coordinated methanol molecule and a monodentate pivalate. The latter two are connected by a hydrogen bond, thus stabilizing the monodentate carboxylate moiety. Redox behaviors (CV) of 1 and 3 are grossly similar, each undergoing a quasi-reversible reduction process at E1/2 ) -0.03 and -0.11 V, respectively, versus a Ag/AgCl reference

Targeted syntheses of homo- and heterotrinuclear complexes involving MII-NiII-MII (M = Ni, Cu, and Pd) nonlinear core: Structure, spectroscopy, magnetic and redox studies

Homo- and heterotrinuclear complexes [LNi{M(Ln)}2](ClO4)2 H2O involving NiIIMII 2 nonlinear cores (M = Ni, Cu, and Pd) (1-6) have been synthesized by a single-pot reaction when the oximato metal complexes [MLn(H2O)]ClO4 (HLn are tridentate oxime ligands), prepared in situ in methanol are allowed to react with the precursor nickel(II) complex [LNi(H2O)2] (H2L = N,N0-dimethyl-N,N0-bis(2-hydroxy-3,5- dimethylbenzyl)ethylenediamine). Single crystal X-ray diffraction analysis, and ESI-MS spectroscopy have been used to establish their identities which involve an octahedral Ni(II) site flunked by two metal-oximate moieties, each in a square planar environment. The electronic and molecular structures of these compounds are interesting due to a synergistic bonding mechanism operative through the deprotonated oxime and the phenolate oxygen atoms via the metal centers.......

Bi- and trinuclear copper(II) complexes of a sterically constrained phenol-based tetradentate ligand: syntheses, structures, and magnetic studies

Cu(II) complexes of a sterically constrained phenol-based tetradentate N2O2 ligand 1,4-bis(2-hydroxy-3,5-dimethylbenzyl)piperazine (H2L) are reported. The assocd. anions of the Cu(II) ion precursors have profound influence on the stoichiometry of the products. Thus, with perchlorate ion, the product is binuclear [Cu2L2] (1), while with coordinating anions viz. Cl- and N3-, [Cu3L2Cl2(H2O)]×0.5H2L (2) and [Cu3L2(N3)2(MeOH)]×4H2O (3) have triangulo trinuclear compn. The syntheses, x-ray structures, and spectroscopic and magnetic properties of these complexes are described..