scholarly journals The biosynthesis of biotin in growing yeast cells: The formation of biotin from an early intermediate

1966 ◽  
Vol 101 (3) ◽  
pp. 598-600 ◽  
Author(s):  
M A Eisenberg
Keyword(s):  
Biological Activity ◽  
Penicillium Chrysogenum ◽  
Previous Investigation ◽  
Specific Activity ◽  
Yeast Cells ◽  
Pimelic Acid ◽  
Avidin Biotin Complex

1. Yeast cells grown in the presence of an unknown radioactive biotin vitamer produced by Penicillium chrysogenum incorporated the vitamer into the newly synthesized biotin. 2. The biotin was isolated as the avidin-biotin complex and after hydrolysis the biological activity and radioactivity were shown to be coincidental. 3. The specific activity of the biotin was identical with that of the pimelic acid used in a previous investigation to label the unknown vitamer. 4. The role of the unknown biotin vitamer as an intermediate in biotin biosynthesis is discussed.

scholarly journals An early intermediate in the biosynthesis of biotin: Incorporation studies with [1,7-14C2]pimelic acid

1966 ◽  
Vol 101 (3) ◽  
pp. 601-606 ◽  
Author(s):  
M A Eisenberg ◽  
R Maseda
Keyword(s):  
Penicillium Chrysogenum ◽  
Pimelic Acid ◽  
Culture Filtrates ◽  
High Yields ◽  
Intermediate Role

1. An unknown biotin vitamer was obtained in high yields in culture filtrates of Penicillium chrysogenum. 2. Production of this vitamer and desthiobiotin is controlled by the biotin concentration in the medium. 3. The unknown vitamer becomes labelled when the organism is grown in the presence of radioactive pimelic acid. 4. Chromatographic procedures were developed for the purification of the radioactive vitamer. 5. The vitamer is extremely stable in concentrated acid but gives rise to new vitamers under certain conditions. 6. The intermediate role of this vitamer in the synthesis of biotin is discussed.

scholarly journals The role of the arginine-B22 residue in insulin action

1981 ◽  
Vol 195 (3) ◽  
pp. 765-768 ◽  
Author(s):  
K Rose ◽  
A R Rees ◽  
C S Drake ◽  
R E Offord
Keyword(s):  
Biological Activity ◽  
Blood Sugar ◽  
Insulin Action ◽  
Specific Activity ◽  
Arginine Residue ◽  
Side Chain ◽  
Opposite Charge ◽  
Lower Blood ◽  
Blood Sugar Concentration

We describe the modification of the side chain of the arginine-B22 residue of insulin by the N8N9-(1, 2-dihydroxycyclohex-1,2-ylene) group and by the adipoyl group. These are the first insulin derivatives described that contain a modified arginine residue in an otherwise unaltered molecule. When tested for their ability to lower blood sugar concentration, both modified insulins showed a specific activity indistinguishable from that of insulin. In view of the fact that the substituent groups involved are very bulky and in one case of opposite charge to that of the side chain, the retention of biological activity casts doubt on the idea, previously generally accepted, that the arginine-B22 residue is essential to the activity of the hormone.

Biological activity of novel thyroid hormone analogues: role of Na+ taurocholate cotransporting polypeptide in liver selectivity

2015 ◽  
Author(s):  
Giulia Brigante ◽  
Bo Carlsson ◽  
Simone Kersseboom ◽  
Robin P Peeters ◽  
Theo J Visser
Keyword(s):  
Biological Activity ◽  
Thyroid Hormone

scholarly journals Studies on the Role of Methylated Bases in the Biological Activity of Soluble Ribonucleic Acid

1964 ◽  
Vol 239 (9) ◽  
pp. 2918-2926
Author(s):  
Alan Peterkofsky ◽  
Celia Jesensky ◽  
Arthur Bank ◽  
Alan H. Mehler
Keyword(s):  
Biological Activity ◽  
Ribonucleic Acid

scholarly journals Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata

2021 ◽  
Vol 22 (12) ◽  
pp. 6557
Author(s):  
Li-Ying Ren ◽  
Heng Zhao ◽  
Xiao-Ling Liu ◽  
Tong-Kai Zong ◽  
Min Qiao ◽  
...  
Keyword(s):  
Biological Activity ◽  
Abscisic Acid ◽  
Lignin Degradation ◽  
Molecular Mechanisms ◽  
Receptor Protein ◽  
Gastrodia Elata ◽  
Upregulated Genes ◽  
Aba Biosynthesis ◽  
Seed Coats

Gastrodia elata is a well-known medicinal and heterotrophic orchid. Its germination, limited by the impermeability of seed coat lignin and inhibition by abscisic acid (ABA), is triggered by symbiosis with fungi such as Mycena spp. However, the molecular mechanisms of lignin degradation by Mycena and ABA biosynthesis and signaling in G. elata remain unclear. In order to gain insights into these two processes, this study analyzed the transcriptomes of these organisms during their dynamic symbiosis. Among the 25 lignin-modifying enzyme genes in Mycena, two ligninolytic class II peroxidases and two laccases were significantly upregulated, most likely enabling Mycena hyphae to break through the lignin seed coats of G. elata. Genes related to reduced virulence and loss of pathogenicity in Mycena accounted for more than half of annotated genes, presumably contributing to symbiosis. After coculture, upregulated genes outnumbered downregulated genes in G. elata seeds, suggesting slightly increased biological activity, while Mycena hyphae had fewer upregulated than downregulated genes, indicating decreased biological activity. ABA biosynthesis in G. elata was reduced by the downregulated expression of 9-cis-epoxycarotenoid dioxygenase (NCED-2), and ABA signaling was blocked by the downregulated expression of a receptor protein (PYL12-like). This is the first report to describe the role of NCED-2 and PYL12-like in breaking G. elata seed dormancy by reducing the synthesis and blocking the signaling of the germination inhibitor ABA. This study provides a theoretical basis for screening germination fungi to identify effective symbionts and for reducing ABA inhibition of G. elata seed germination.

scholarly journals Differential Role of Threonine and Tyrosine Phosphorylation in the Activation and Activity of the Yeast MAPK Slt2

2021 ◽  
Vol 22 (3) ◽  
pp. 1110
Author(s):  
Gema González-Rubio ◽  
Ángela Sellers-Moya ◽  
Humberto Martín ◽  
María Molina
Keyword(s):  
Cell Wall ◽  
Biological Activity ◽  
Biological Significance ◽  
Mitogen Activated Protein Kinase ◽  
Activation Loop ◽  
High Increase ◽  
Dual Specificity ◽  
Mitogen Activated Protein ◽  
Full Activation

The Mitogen-Activated Protein Kinase (MAPK) Slt2 is central to signaling through the yeast Cell Wall Integrity (CWI) pathway. MAPKs are regulated by phosphorylation at both the threonine and tyrosine of the conserved TXY motif within the activation loop (T190/Y192 in Slt2). Since phosphorylation at both sites results in the full activation of MAPKs, signaling through MAPK pathways is monitored with antibodies that detect dually phosphorylated forms. However, most of these antibodies also recognize monophosphorylated species, whose relative abundance and functionality are diverse. By using different phosphospecific antibodies and phosphate-affinity (Phos-tag) analysis on distinct Slt2 mutants, we determined that Y192- and T190-monophosphorylated species coexist with biphosphorylated Slt2, although most of the Slt2 pool remains unphosphorylated following stress. Among the monophosphorylated forms, only T190 exhibited biological activity. Upon stimulation, Slt2 is first phosphorylated at Y192, mainly by the MAPKK Mkk1, and this phosphorylation is important for the subsequent T190 phosphorylation. Similarly, dephosphorylation of Slt2 by the Dual Specificity Phosphatase (DSP) Msg5 is ordered, with dephosphorylation of T190 depending on previous Y192 dephosphorylation. Whereas Y192 phosphorylation enhances the Slt2 catalytic activity, T190 is essential for this activity. The conserved T195 residue is also critical for Slt2 functionality. Mutations that abolish the activity of Slt2 result in a high increase in inactive Y192-monophosphorylated Slt2. The coexistence of different Slt2 phosphoforms with diverse biological significance highlights the importance of the precise detection of the Slt2 phosphorylation status.

scholarly journals Role of peptide backbone conformation on biological activity of chemotactic peptides.

1991 ◽  
Vol 266 (28) ◽  
pp. 18460-18468
Author(s):  
A.R. Dentino ◽  
P.A. Raj ◽  
K.K. Bhandary ◽  
M.E. Wilson ◽  
M.J. Levine
Keyword(s):  
Biological Activity ◽  
Peptide Backbone ◽  
Backbone Conformation ◽  
Chemotactic Peptides ◽  
Peptide Backbone Conformation

The biological activity of glucagon–phospholipid complexes

1983 ◽  
Vol 61 (7) ◽  
pp. 688-691 ◽  
Author(s):  
J. J. Liepnieks ◽  
P. Stoskopf ◽  
E. A. Carrey ◽  
C. Prosser ◽  
R. M. Epand
Keyword(s):  
Biological Activity ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Bovine Brain ◽  
Water Soluble ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Dimyristoyl Phosphatidylcholine ◽  
Lipoprotein Complex ◽  
Stimulation Of

Glucagon can form water-soluble complexes with phospholipids. The incorporation of glucagon into these lipoprotein particles reduces the biological activity of the hormone. The effect is observed only at temperatures below the phase transition temperature of the phospholipid and results in a decreased stimulation of the adenylate cyclase of rat liver plasma membranes by the lipoprotein complex as compared with the hormone in free solution. Two- to five-fold higher concentrations of glucagon are required for half-maximal stimulation of adenylate cyclase when the hormone is complexed with dimyristoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or bovine brain sphingomyelin. A possible role of lipoprotein-associated hormones in the development of insulin resistance is discussed.

EFFECT OF OXIDATION ON BIOLOGICAL AND IMMUNOLOGICAL ACTIVITY OF PORCINE PARATHYROID HORMONE

1974 ◽  
Vol 63 (1) ◽  
pp. 117-124 ◽  
Author(s):  
J. L. H. O'RIORDAN ◽  
J. S. WOODHEAD ◽  
G. N. HENDY ◽  
J. A. PARSONS ◽  
C. J. ROBINSON ◽  
...  
Keyword(s):  
Biological Activity ◽  
Parathyroid Hormone ◽  
Cysteine Oxidation ◽  
Subsequent Reduction ◽  
Immunological Activity ◽  
Parathyroid Hormones ◽  
Methionine Residue

SUMMARY The presence of a single methionine in porcine parathyroid hormone, at position 8, permitted assessment of the role of this residue separate from the second methionine residue found at position 18 of bovine and human parathyroid hormones. Oxidation of the solitary methionine of porcine parathyroid hormone to the sulphoxide destroyed biological activity, but this was restored by subsequent reduction with cysteine. Oxidation of the hormone did not, however, affect its immunological activity; therefore, oxidation of the hormone may bring about dissociation of biological and immunological activity.

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