Basic proteins from the acidic extract of bovine spinal cord

One hundred years of American Women in biochemistry *

The occasion of ASBMB's 100th anniversary provides an opportunity to consider the history and accomplishments of women biochemists over the past century. American women in biochemistry have ranged from the highly visible, such as Nobel Prize winners Gert Cori and Gertrude Elion, to those who contributed in relative obscurity to equally dramatic breakthroughs. Women with Ph.D.s in biochemistry established departments of public health, nutrition, and home economics when more prestigious academic departments were not open to them. As in all fields of science, women have made great progress in biochemistry in recent years, and ASBMB reflects that progress; the past, current, and incoming presidents of the Society are all women. The data and biographical information presented here should provide a basis for inclusion of more women in recounting the history of biochemistry.

Sequence determinants of modified cobra venom neurotoxin which induce immune resistance to experimental allergic encephalomyelitis: molecular mechanisms for immunologic action

A nontoxic, iodoacetamide-modified cobratoxin derivative (CAM-NTX) induced resistance to experimental allergic encephalomyelitis (EAE) in guinea pigs. Resistance was retained after trypsin digestion and shown to reside in N-terminal and central peptides of CAM-NTX. A similarly modified protein cardiotoxin (CAM-CTX), representative of proteins homologous with cobratoxin, was not immunosuppressive. Depressed clinical symptoms in EAE-resistant animals correlated with reduced lymphocytic infiltration of the brain. Antibody to myelin basic protein (MBP) was reduced in immunosuppressed animals. The immunoinhibitory determinants in CAM-NTX may mimic immune response suppressor proteins (SIRS-alpha 7) and the EAE-resistance region of MBP.

Experimental allergic encephalomyelitis in mice: presence of myelin basic protein in cerebrospinal fluid

The concentration of myelin basic protein (MBP) in cerebrospinal fluid (CSF) correlates with the development of experimental allergic encephalomyelitis following intradermal injection with encephalitogen in adjuvant; MBP is absent in controls inoculated with adjuvants only. The presence of MBP is a sensitive indicator of disease inasmuch as CNS-inoculated mice with neurologic signs had an average of 0.29 ng/microliter of MBP in their CSF and controls, including normal or adjuvants only, had an average of 0.03 ng/microliter. The amount present per microliter of CSF, as well as the absolute amount, obtained from an individual mouse do not always reflect the severity of disease as indicated by clinical signs and the pathology observed in a sampling of the neuraxis. The presence of MBP does correlate with demyelination, although the extent of pathology observed by light microscopy in the mouse model is minimal, associated only with the inflammatory response, and does not extend beyond the zone of the perivascular cuff.

Chronic Theiler's virus infection in mice: appearance of myelin basic protein in the cerebrospinal fluid and serum antibody directed against MBP

Myelin basic protein (MBP) appears frequently in the cerebrospinal fluid (CSF) of mice with chronic demyelination following intracerebral infection with Theiler's murine encephalomyelitis virus (TMEV); antibody to MBP can frequently be found in the sera. The peaks of the immune responses to both MBP and TMEV coincide with the time course of the clinical signs of disease. Adsorption of mouse sera with TMEV or MBP indicate the non-identity of the antigens and the specificity of the antisera as measured by ELISA. Immunoblot analysis of sera confirmed the ELISA findings. The mechanism of induction of antibody directed against MBP and its role in TMEV-associated demyelination remain to be determined.

Myelin basic protein and demyelinating diseases

Myelin basic protein (MBP) is a major protein component of myelin sheath. Primarily because of its ability to induce experimental allergic encephalomyelitis (EAE) in animals, this protein has been considered to play an important role in the pathogenesis of multiple sclerosis (MS), which is one of the most common demyelinating diseases. Its precise measurement in the cerebrospinal fluid (CSF) has been uncommonly difficult, mainly due to immunoheterogeneity of MBP or MBP-like material. More recently, highly sensitive radioimmunoassay techniques utilizing well-characterized antisera have been developed that facilitated its use in the management of MS. The clinical course of MS is highly variable, and the disease is characterized by periods of remission and relapses. Many studies have demonstrated the release of MBP during relapses and elevated levels of MBP in the CSF can be detected if lumbar puncture is performed within 7 days of the onset of neurologic symptoms suggestive of MS. However, the presence of MBP is not an absolute indicator of MS, as elevated MBP levels are also frequently observed in other demyelinating diseases.

Molecular size of myelin basic protein immunoactivity in spinal fluid

The molecular size of myelin basic protein (MBP) immunoactivity in spinal fluid from patients with multiple sclerosis, acute stroke or who had gone through neurosurgery was determined by gel filtration. Gel filtration fractions were analysed for MBP by radioimmunoassay. Spinal fluid from all patients demonstrated a broad range of MBP immunoactivity. The neurosurgery and stroke cases had high MBP immunoactivity in the higher molecular range, around 67 000 daltons. The spinal fluid from MS patients had increased levels of low molecular size MBP immunoactivity, around 10-13 000 daltons. The results suggest that different forms of demyelinating processes give rise to various kinds of MBP fragments and/or different proteolytic activity on MBP within the spinal fluid space.

Separation of myelin basic protein peptide 43-88 and its fragments by analytic and preparative high-performance liquid chromatography

Reversed-phase (RP) high-performance liquid chromatography (HPLC) using a solvent mixture of triethylammonium formate buffer and methanol permitted the rapid separation of myelin basic protein peptide 43-88 and a mixture of synthetic fragments from this peptide. The elution times for some of the peptides were markedly affected by minimal changes in the solvent mixture. Attempts to separate the same peptides by gel permeation HPLC resulted in poor resolution and an aberrant elution pattern unrelated to molecular size. With the use of the volatile triethylammonium formate buffer in the RP-HPLC, material could be more readily separated and easily recovered by freeze-drying. Analysis of the components separated by this system of RP-HPLC demonstrated that the preparation of normal human BP peptide 43-88 results in an admixture of peptides 43-87 and 43-88. This procedure of RP-HPLC should make it possible to analyze the degradation of myelin basic protein peptide 43-88 and to isolate the degradation products for characterization.

Application of high performance liquid chromatography to the preparation of encephalitogenic myelin basic protein

Two preparations of myelin basic protein (MBP) were derived from an acid excretion of chloroform-methanol defatted bovine spinal cord. The first was purified by ion-exchange chromatography using guanidine-HCl; the second, by high performance liquid chromatography (HPLC) using a triethylamine eluant. Both methods of preparation yield MBP which is identical on acid-urea polyacrylamide gel electrophoresis and which has identical encephalitogenic potency. Because of the greater time-efficiency of the HPLC system with no deleterious side effects due to buffer contamination, this latter method can be recommended for MBP purification.

Inhibition of experimental allergic encephalomyelitis by carrier administered prior to challenge with encephalitogenic peptide-carrier conjugate

Guinea pigs can be rendered unresponsive to experimental allergic encephalomyelitis (EAE) challenge by prior injections of myelin basic protein (BP) or peptides derived from BP. The synthesized tryptophan-containing peptide (TrpP, corresponding to residues 114-122) which is the primary encephalitogenic sequence in BP (for guinea pigs) had been conjugated to the non-central nervous system protein bovine serum albumin (BSA) and used for EAE challenge. It has been shown in this study that prechallenge treatment with the BSA carrier alone can significantly inhibit the induction of EAE by TrpP-BSA conjugate. That carrier treatment is immunologically specific was determined when prior treatment with cytochrome c did not protect animals from EAE challenge with TrpP conjugated to BSA. In addition, in disease induced with BP or TrpP, and while TrpP did protect guinea pigs challenged with TrpP, it did not protect those challenged with BP. This last finding raises the possibility of a second encephalitogenic sequence in BP or an important role for the carrier in the TrpP conjugate.

Bovine peripheral nervous system myelin P2 protein: chemical and immunological characterization of the cyanogen bromide peptides

Cleavage of bovine P2 protein by cyanogen bromide (CNBr) produced peptide fractions CN1, CN2, and CN3 which were isolated by gel filtration chromatography. CN2 was found to contain two NH2-terminals (lysine and valine) and accounted for both of the cysteine residues of P2. When reduced carboxymethylated P2 (RCM-P2) was digested with CNBr, peptides CN1 and CN3 were obtained as were (1) a peptide with NH2-terminal lysine (Lys) that contained no homoserine and only one cysteine residue and (2) a peptide with NH2-terminal valine (Val) that was co-eluted with CN3. These data and the chemical characterization of all the CNBr peptides obtained from P2 and RCM-P2 suggest that isolated P2 protein has a structure composed of the CNBr peptides in the order CN3-CN1-CN2(Val)-CN2(Lys) with an intrachain disulfide bond between the cysteine residues located in the two constituent peptides of CN2, CN2(Lys) and CN2(Val). To locate the neuritogenic region(s) within the P2 protein structure, CN1, CN2, and CN3 were tested for the ability to induced experimental allergic neuritis (EAN) in Lewis rats. The disease-inducing sites of P2 protein were found only in CN1; neither CN2 nor CN3 produced disease. EAN induced by CN1 was comparable to that induced with P2 protein as determined by disease onset, clinical symptoms, and histologic lesions.

Molecular features of immunoreactive myelin basic protein in cerebrospinal fluid of persons with multiple slcerosis

The molecular weight of the myelin basic protein (BP)-like material appearing in cerebrospinal fluid (CSF) of 2 persons with active-phase multiple sclerosis (MS) and 3 with recent cerebral infarctions was determined by gel filtration chromatography under acidic conditions. Column fractions were examined by radioimmunoassay for BP peptide 43-88 antigen as well as for binding activity to BP. Material cross-reactive with BP peptide 43-88 eluted over a wide spectrum of molecular weights. Greater representation of lower molecular weight species occurred in MS. Fractionated CSF from 2 patients with MS and 2 with cerebral infarction contained binding activity, presumably antibody, to BP which was greater than that in unfractionated CSF. Binding to BP was also examined in unfractionated CSF from 70 persons, including 16 with MS and 36 with other neurological diseases. Although CSF from MS patients showed higher binding, the presence of BP binding activity was not specific for MS. Our findings suggest that the antigen cross-reacting with BP and its fragments in CSF appears in a spectrum of molecular weight species, with lower forms predominating in MS. The detection of binding activity to BP as well as its enhancement by treatment at low pH suggest that the BP-like antigen in CSF may exist in free as well as in complexed forms.

Immunosuppression of experimental allergic encephalomyelitis in guinea pigs by antibrain and antithymocyte heteroantisera

Experimental allergic encephalomyelitis (EAE), induced by central nervous system (CNS) myelin basic protein (MBP) in adjuvant, is considered a thymus dependent autoimmune disease. Brain contains the thymic antigen, thy 1. The possibility that brain associated anti thy 1 immunoglobulin may be provoked in certain pathologic conditions of the CNS suggested a comparative evaluation of brain and thymocyte antisera on the development of EAE. Antisera produced in rabbits against brain from guinea pigs, rats and mice or fetal guinea pig thymus were highly reactive against thy 1 containing cells when assessed by indirect immunofluorescent staining or complement-mediated cell lysis. Treatment of guinea pigs with heteroantisera to guinea pig and mouse, but not to rat brain, for 3 days around the time of MBP sensitization markedly reduced physical signs of disease, particularly paralysis, but had little effect on the development of inflammatory lesions in the CNS. Anti-guinea pig thymocyte sera eliminated all physical signs of EAE with only residual pathology. These results establish the relative immunosuppressive effect of brain and thymocyte antisera in EAE and corroborate the thymus-dependent nature of EAE in guinea pigs.

Induction of allergic encephalomyelitis in rhesus monkeys treated with anti monkey thymocyte sera

Treatment with rabbit anti-moneky thymus cell sera whether limited (3 days) or extensive (15 days), did not alter the development of experimental allergic encephalomyelitis (EAE) in rhesus monkeys challenged with myelin basic protein or central nervous system tissue (CNS) when compared to similarly challenged control monkeys treated with normal rabbit serum. No consistent difference in disease incidence or intensity as measured by incubation period, neurologic signs or CNS pathology was observed between experimental and control monkeys. This finding is in contrast to previous reports on the efficacy of ATS treatment in prevention of EAE in rodents.

E rosette-forming lymphocytes in multiple sclerosis patients. Basic protein stimulation of rosette-forming cells

"Total" and "active" T cells were enumerated using sheep red blood cell (SRBC) rosetting technique. The percentages of "total" and "active" T lymphocytes were not significantly different in multiple sclerosis patients as compared to other neurological disorders and/or healthy controls. However, the number of "avid" T cells binding more than three SRBC was significantly increased in MS patients. Active E rosette test has shown hypersensitization to myelin basic protein in 50% MS patients and 31% OND patients. All healthy controls studied, except one had negative response.

Molecular bases for the difference in the potency of myelin basic protein from different species in Lewis rats

The results of this study define the chemical bases for the difference in the encephalitogenic potency reported for the bovine and guinea pig myelin basic proteins. Studies with synthetic peptides showed that the sequence of peptide S53, H-Ser-Gln-Arg-Ser-Gln-Asp-Glu-Asn-OH, which is native to the guinea pig basic protein, is the minimum amino acid sequence necessary for inducing EAE in Lewis rats. The results of this study further showed that specific sequence modifications rendered the native bovine sequence highly encephalitogenic.

Conformational changes induced by ionic strength and pH in two bovine myelin basic proteins

The structures of two biologically different myelin proteins, A1 from the central nervous system and P2 from the peripheral nervous system, were investigated. Both proteins were isolated from nerve tissues. Conformational changes in the homogeneous proteins were examined in aqueous solutions by means of circular dichroism measurements. The secondary structures of both proteins proved to be very stable between pH 2.5 and pH 11.7. Unlike the P2 protein, the A1 protein is stable up to pH 13 without detectable conformational changes. The stereochemistry of the polypeptide chains of both proteins is markedly different in the presence of urea. While the value of theta222 for the A1 protein changes linearly with increasing urea concentration, a sigmoidal curve was obtained for the P2 protein. The observed differences in the dichroic properties of the basic myelin proteins A1 and P2 indicate the possibility of further structure - function correlations.

Experimental allergic encephalomyelitis in Lewis rats: chemical synthesis of disease-inducing determinant

Two amino acid sequences from the same regions of guinea pig and bovine myelin basic protein which induce experimental allergic encephalomyelitis in Lewis rats were synthesized. The sequences of these two regions may be defined by residues 69 to 84 of the bovine basic protein. The encephalitogenic sequence from guinea pig basic protein (peptide S49), H-Gly-Ser-Leu-Pro-Gln-Lys-Ala-Gin-Arg-Pro-Gin-Asp-Glu-Asn-OH, is a much more potent encephalitogen than that of H-Gly-Ser-Leu-Pro-Gln-Lys-Ala-Gln-Gly-His-Arg-Pro-Gln-Asp-Glu-Asn-OH (peptide S8) found in the bovine protein. The primary structures of the two determinants are similar; however, a Gly-His deletion from the guinea pig sequence is noted. Study of the encephalitogenicity of peptide S49, peptide S8, and the parent proteins suggests that the difference in the encephalitogenic potency of the parent proteins in Lewis rats is due to a natural modification in the primary structure of their respective encephalitogenic determinants.

Autoimmune disease antigens

The first step towards understanding the cellular interaction which results in autoimmune disease is to determine what triggers the recognition between a specific autoimmune antigen determinant and the cellular receptor. In this review, we have focused on the antigen inducing experimental allergic encephalitis (EAE) because the antigen has been characterized and a relatively large body of information on its biological activities has been accumulated. Clearly, a specific allergic encephalitis-producing determinant is present and is represented on a relatively small portion of the molecule. The determinant induces a wide variety of biological reactivities, some of which are classed as cellular mediated. An attempt is made to dissect activities such as blast transformation (BT), migration inhibitory factor (MIF), in vivo delayed type hypersensitivity reaction (DTH) and EAE and to relate them to the structural requirements which the determinants possess. The complexities which arise indicate that subpopulations of cells with different receptor activities may respond selectively and that recognition of the receptor is produced by an EAE determinant consisting of three amino acids in a specific linear sequence. Furthermore, under experimental circumstances the EAE activity can be dissociated from the other activities (BT, MIF, DTH), indicating that while these tests are used generally to follow various human autoimmune disease activities, they may represent the reaction of a broad spectrum of cells.

Solution behavior, circular dichroism and 22 HMz PMR studies of the bovine myelin basic protein

Bovine myelin basic protein has been investigated with regard to its solution behavior, circular dichroism and 220 MHz PMR spectral properties. At pH 4.8 gamma/2=0.1 acetate buffer, light scattering yielded a Mr of 17 700 and a virial coefficient of 1.0-10(-4) mol-ml/g2. Above pH 7.0 the protein was found to aggregate to higher mol. wt species. Sedimentation experiments at pH 4.8 yielded s degrees 20,w of 1.27 S at gamma/2=0.1 and 1.46 S at gamma/2=0.35. The diffusion coefficient determined from ultracentrifugal experiments was 7.25-10(-7) cm2/s at gamma/2=0.1 and 0.35. The value of f/f0 from diffusion at pH 4.8 and gamma/2=0.35 was 1.64, corresponding to an axial ratio of 11 to 1. The radius of gyration was calculated as 4.28 nm and the root mean square end to end distance was 10.5 nm. At pH 9.0, gamma/2=0.1, s degrees 20,w was 1.71 S and D degrees 20,w was estimated at 7.4-10(-7) cm2/s. The behavior at pH 9.0 reverted to the behavior at pH 4.8 when the pH was readjusted. The E1%/1cm=5.64 at 276.4 nm and 225 at 196 nm. Titration of the protein with trifluoroethanol elicited three distinct regions of conformation stability having increasing helical content as the mol fraction of trifluoroethanol increased. The results of the present study have permitted some comparison of analogous properties and conformational behavior with the basic membrane protein cytochrome c.