Characterization of the normal alpha 1-antitrypsin allele Vmunich: a variant associated with a unique protein isoelectric focusing pattern.

alpha 1-Antitrypsin (alpha 1AT), the major serum inhibitor of neutrophil elastase, is a highly polymorphic protein associated with isoelectric focusing (IEF) patterns typical for each variant. alpha 1AT Vmunich, a previously unreported normal alpha 1AT variant, has a unique IEF banding pattern in which the 7 and 8 alpha 1AT protein bands focus with the normal M-type 7 and 8 bands, despite the fact that the major fraction of the Vmunich protein focuses in the "V" region of the IEF gel. To characterize the molecular basis of this variant and its unique IEF pattern, DNA sequence analysis of the coding exons of the Vmunich alpha 1AT gene was carried out using the polymerase chain reaction. The Vmunich allele differed from the common normal M1(Val213) alpha 1AT allele by a single nucleotide substitution of cytosine for adenosine, with the resultant amino acid change Asp2 GAT----Ala GCT. Inheritance of the allele was confirmed by family analysis using allele-specific amplification with the polymerase chain reaction. The Asp2----Ala mutation explains the cathodal position of the Vmunich protein on IEF, as there is a substitution of a negatively charged amino acid by a neutral one.(ABSTRACT TRUNCATED AT 250 WORDS)     

Albumin Paris 2: a new genetic variant distinguished by isoelectric focusing.

Until recently, the characterization of genetic variants of human serum albumin was performed by electrophoretic typing prior to the determination of their amino acid substitutions. We describe a procedure using isoelectric focusing in the presence of urea for the analysis of the genetic variation of albumin. This procedure allowed a clear distinction of a new variant, previously found to be identical with albumin Sondrio according to its relative electrophoretic mobilities at 3 pHs. This new variant, the third rare albumin allotype identified in the Ile-de-France region, was called albumin Paris 2.     

Characterization of alpha-1-antitrypsin by isoelectric focusing on an ultrathin polyacrylamide gel layer

Summary Through the use of ultrathin layer polyacrylamide gel isoelectric focusing it is possible to obtain a resolution of the bands of ₁AT so as to be able to easily recognize all six PiM subtypes. The optimal resolution of the PiM subtypes is obtained without deforming the pattern of the Pi phenotypes. In addition to high resolution, ultrathin layer polyacrylamide gel isoelectric focusing permits a notable reduction of fees to 1/5 of the usual.     

Characterization of cellulases in an extracellular fraction from Trichoderma reesei under conditions of isoelectric focusing (IEF)

Abstract A cellulase-containing fraction present in the culture fluid of Trichoderma reesei grown on cellulose was obtained by fractionated centrifugation. The buoyant density of this fraction was D = 1.060 g/ml. Its ultrastructural properties, as detected by transmission electron microscopy, are given. The fraction consists of membrane vesicles attached to a carbohydrate polymer. This polymer is positive to Ruthenium red staining.
The effect of urea on the extraction and separation of acidic cellulases from this fraction is described. Linear gradient gels for both urea (up to 8.0 M urea) and polyacrylamide gels (up to 30%) were used to determine adequate separation conditions for isoelectric focusing (IEF) in a polyacrylamide gel matrix. The effect of urea on the extraction and separation conditions was tested by titration curves. In the presence of 6.0−8.0 M urea, the main cellulase-containing hydrolase complex (pI_app4.2) from this fraction is split into 3 isoenzymes and a further cellulase (pI 5.65).     

Characterization of normal and abnormal variants of galactose-1-phosphate uridylyltransferase (EC 2.7.7.12) by isoelectric focusing

Isoelectric focusing (IEF) in polyacrylamide gels has been used to study the isozymes of human galactose-1-phosphate uridylyltransferase (GALT) in erythrocytes and fibroblasts. In addition to the usefulness of IEF in differentiating normal, Duarte variant, and galactosemic homozygotes and heterozygotes, the ability of IEF to distinguish the residual GALT activity in two different galactosemic fibroblast lines and in revertants from them is demonstrated.     

Investigations on the PGM 1 a polymorphism (phosphoglucomutase-EC 2.7.5.1) by isoelectric focusing

Summary The determination of phosphoglucomutase (PGM₁) phenotypes was performed by isoelectric focusing on samples from 1678 unrelated individuals from Hessen, Germany. Ten common phenotypes are considered as gene products of four alleles at the PGM₁ locus with the following frequencies: PGM ₁ ^a1 =0.6305, PGM ₁ ^a2 =0.1844, PGM ₁ ^a3 =0.1320, and PGM ₁ ^a4 =0.0530. Twenty-two different mating types were observed in 113 families with 202 children. The segregation of the phenotypes in the offspring supports the assumed way of autosomal codominant inheritance. The example of a silent allele (PGM ₁ ⁰ ) as well as a rare variant (PGM ₁ ⁷ ) is reported.     

Composition of an isoelectric focusing gel yielding a broad pH gradient.

An isoelectric focusing gel system is described which produces a pH gradient spanning the range 4–9. When chick brain mitochondrial polypeptides were focused on such a gel, extra polypeptide spots were observed in the basic region which were not seen in a gel prepared by conventional methods.     

Phosphoglucomutase (PGM1) subtypes in a Finnish population determined by isoelectric focusing in agarose gel

The red cell enzyme phosphoglucomutase first locus (PGM1) phenotypes of 639 adult Finns were determined by isoelectric focusing in agarose gel. All the ten commonly occurring phenotypes were detected and the frequencies of the four alleles at the PGM1 locus were as follows: PGMa11 = 0.5313, PGMa21 = 0.1800, PGMa31 = 0.2199 and PGMa41 = 0.0689. The PGM1 phenotypes of 221 mothers with 228 offspring were in accordance with autosomal codominant inheritance.     

A new hereditary variant of the PGM1 erythrocyte enzyme system determined by isoelectric focusing

Summary A new variant of the PGM _a ¹ erythrocyte enzyme system not identical with the known variants of the system has been detected in the hemolyzed red blood cells of a healthy blood donor by isoelectric focusing. Using this technique the variant is represented by two bands, a strong and slow one more cathodically located than the a3 band and a weak one in the position of the a2 band. Using agarose thinlayer or acetate foil electrophoresis the variant is represented only by a minimal cathodic broadening of the PGM₁ 1 band and therefore it is easily overlooked. Investigation of the propositus' family shows that the variant occurs combined with the common alleles PGM ₁ ^a1 , PGM ₁ ^a2 , and PGM ₁ ^a3 and that it has an autosomal dominant inheritance. Obviously the variant has a very low frequency.     

Characterization of unstable hemoglobin A1c complexes by dynamic capillary isoelectric focusing

Glucose spontaneously reacts with hemoglobin amino groups to produce unstable Schiff base complexes that can dissociate or rearrange to form stable Amadori products. We used dynamic capillary isoelectric focusing and boronate affinity chromatography to assess the formation and dissociation of unstable hemoglobin complexes in vitro. Formation was studied by incubating erythrocytes at 37°C for up to 24h in phosphate-buffered saline (PBS) supplemented with 0 to 55.6 mmol/L glucose. Dissociation was studied by incubating glucose-loaded erythrocytes in PBS without glucose. Dynamic capillary isoelectric focusing separated hemoglobin A1c into two subfractions identified as A1c1 and A1c2. The A1c1 subfraction contained both stable and unstable hemoglobin complexes. The A1c2 subfraction contained only unstable hemoglobin complexes. Both subfractions quantitatively increased in the presence of glucose and decreased in its absence. Rates of increase and decrease were faster and time to equilibrium was shorter for A1c2 (~4 h) compared with A1c1 (~20 h). Unstable hemoglobin complexes did not bind to boronate affinity columns but instead eluted intact in A1c1 and A1c2 subfractions from nonglycated affinity fractions. Cyanoborohydride reduction confirmed the presence of Schiff base complexes. Evidence of multiple unstable hemoglobin complexes with different rates of glycation suggests that new models are needed to describe nonenzymatic hemoglobin glycation.     

Orosomucoid (ORM) typing by isoelectric focusing: an analysis of ORM haplotypes

A new separator isoelectric focusing method for typing of orosomucoid (ORM) was developed. This method provided a superior resolution of ORM patterns: two close bands of ORM1*5.2 products were clearly separated. A total of 364 subjects from Okinawa (Japan) were classified into 21 ORM phenotypes determined by 6 ORM1 and 7 ORM2 alleles including a polymorphic silent allele, ORM2*QO, and 2 new rare variants, ORM2*18 and ORM2*19. These phenotypes were also explained by 12 ORM haplotypes, half of which were polymorphic.     

Group-specific component (Gc) 'subtypes' of Gc1 by isoelectric focusing in US blacks and whites.

Isoelectric focusing was applied to the Gc polymorphism. In agreement with Constans et al., we found two common 'subtypes' of Gc1 that could not be identified by conventional electrophoretic procedures. They are labeled Gc1F and Gc1S. Gc1F has a slightly lower isoelectric point than Gc1S. In groups of US blacks the allele frequencies were for Gc1F; 0.732 and for Gc1S; 0.147. In whites these figures were 0.149 and 0.572. We also found GcAb in blacks with a frequency of 0.015. The concentrations in serum of Gc protein as measured by radial immunodiffusion did not differ according to phenotype.     

The α1 antitrypsin variant PI*WFINNEYTOWN in a family of Caucasian origin

Summary During a routine screening a slow moving variant PI WFINNEYTOWN was traced in a family of Caucasian origin. The variant is not identical to W SAL and W COL. W FIN was originally detected in an American family of different ethnic origin. It is suggested that heterogeneity exists at the gene level, which is not detectable with conventional methods at the protein level.     

Genetic polymorphism of alpha 1-antitrypsin in green monkeys studied by isoelectric focusing and family analysis

24 variants of alpha 1-antitrypsin (alpha 1-AT) were recognized in sera of 120 wild and capture-born African green monkeys by isoelectrofocusing in Ampholine PAG-plates (pH 4-6.5) and western blotting with antihuman alpha 1-AT serum. All variants had much more cathodal position than human alpha 1-AT and revealed very high microheterogeneity which was slightly different from the observed in human alpha 1-AT. The alpha 1-AT banding pattern allowed to postulate existence of 10 codominant alleles in the Pi locus of African green monkeys. The reality of 8 alleles was proved by family analysis which included 45 monkey birth cases. Two other alleles were absent in the parents available. Thus, alpha 1-AT is the most polymorphic among the known serum proteins of African green monkeys. The latter can be useful for molecular systematics of these primates.     

Microheterogeneity of mammalian haptoglobins in isoelectric focusing.

1. Human haptoglobin type 1-1, porcine haptoglobin, and equine haptoglobin were isolated and purified. 2. These haptoglobins were similar in polyacrylamide gel electrophoresis and in subunit structure but showed microheterogeneity in isoelectric focusing. 3. Isoelectric points of human haptoglobin as determined with photopolymerized gels were found to be 4.03-4.24, of porcine haptoglobin 4.0-4.30, and of horse haptoglobin 3.80-4.15, respectively. 4. Results obtained with chemically polymerized gels were 0.08-0.3 pH units higher. 5. Examined haptoglobins differed also in the ability of complex formation with hemoglobin, in sialic acid content and in antigenic specificity.     

Isoelectric focusing in layers of granulated gels. II. Preparative isoelectric focusing.

A method for preparative isoelectric focusing of 0.1-10 g amounts of proteins is described. For anticonvective stabilization of the pH gradient, layers of granulated gels (E.G. Sephadex or Bio-Gel) of variable length, width and thickness were used either on glass plates or in troughs. Load capacity, defined as the amount of protein per ml gel suspension, was determined to be 5-10 mg per ml for total protein, irrespective of the pH range of the carrier ampholytes. For single proteins load capacities of 0.25-1 mg per ml were found for pH 3-10 carrier ampholytes, and 2-4 mg per ml for narrow pH range ampholytes. Experiments on a quartz plate followed by densitometric evaluation in situ at 280 nm have demonstrated that it is possible to proceed from analytical thin-layer isoelectric focusing to preparative separations without loss of resolution, just by changing the dimension of the gel layer and increasing the protein load. Improved resolution which facilitates isolation of isoelectrically homegenious components could be achieved on a 40 cm long separation distance. The geometry of a layer is favourable to heat dissipation and this permits the use of high voltage gradients. Recovery of the focused proteins is high an elution simple. The efficiency of the method is illustrated by examples showing separations of single proteins and protein mixtures.     

Genetic polymorphism of PIF (parotid isoelectric focusing variant) proteins with linkage to the PPP (parotid proline-rich protein) gene complex

Genetic polymorphism is found among the PIF (parotid isoelectric focusing variant) salivary proteins after separation by prolonged isoelectric focusing in pH 3.5–5.2 urea polyacrylamide slab gels subsequently stained for protein. Two PIF proteins are either present (PIF +) or absent (PIF –) from all salivas. The phenotypes are determined by autosomal inheritance of two alleles, PIF ⁺ and PIF ^–. Gene frequencies in randomly collected samples show marked racial differences: among 148 whites, PIF ⁺ is 0.66 and PIF ^– is 0.34; among 90 blacks, PIF ⁺ is 0.35 and PIF ^– is 0.65; among 78 Chinese, PIF ⁺ is 0.56 and PIF ^– is 0.44. Studies in 41 families including 129 children support the interpretation of control of PIF by a single autosomal locus. In 8 PIF+ × PIF– matings, there were 8 PIF– (6.34 expected) children. In 33 PIF+ × PIF+ matings, there were 7 PIF– (6.70 expected) children. Linkage studies indicate that PIF is closely linked to the proline-rich protein (PPP) gene complex (e.g., for six families, lod score at =0.00 of PIF/G1 is 3.58). In 107 randomly collected samples from whites, PIF is strongly associated with Db (x ₁ ² =20.02; P<0.0001) and Gl (x ₁ ² =12.58; P=0.0005) but not with Pr, Ps, Pm, and Pa proteins. These data (probably reflecting genetic disequilibrium) suggest that PIF may be closer to Db and G1 than to other identified loci of the PPP gene complex. The PPP gene complex includes at least seven genes (and probably more) that produce many acidic and basic proline-rich proteins, constituting about two-thirds of parotid salivary proteins that are thought to have important functions at the tooth surfaces.This study was supported by a grant from the National Institutes of Dental Research (DEO 3658-15). Paper No. 2435 of the Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706.