Helical α/β-depsipeptides with alternating residue types: conformational change from the 11-helix to the 14/15-helix

2016 ◽  
Vol 14 (36) ◽  
pp. 8438-8442 ◽  
Author(s):  
Jaeyeon Lee ◽  
Geunhyeok Jang ◽  
Philjae Kang ◽  
Moon-Gun Choi ◽  
Soo Hyuk Choi
Keyword(s):  
Lactic Acid ◽  
Conformational Change ◽  
The Third ◽  
N Terminus ◽  
Α Helix

Short α/β-depsipeptides of which the third residue from the N-terminus is an (S)-lactic acid residue predominantly adopt 14/15-helical conformations analogous to the α-helix.

scholarly journals The formation of lactic acid in desiccated amphibian muscles

1930 ◽  
Vol 106 (742) ◽  
pp. 122-131 ◽  
Keyword(s):  
Lactic Acid ◽  
Chloride Solution ◽  
Sartorius Muscle ◽  
Silk Thread ◽  
Experimental Procedure ◽  
The Third ◽  
Uniform State ◽  
Cent Sodium ◽  
Geometrical Form ◽  
Determining Factor

The present paper is the third of a series dealing with the effects of freezing and drying on living amphibian muscle (1, 2). In this paper it is shown that simple drying of muscles causes the production of lactic acid, in amount identical with that produced by the corresponding degree of freezing (2). This finding confirms the view expressed in the earlier communications that the effects of freezing and drying are identical, the determining factor in each case being the removal from the muscle of a certain amount of water. Experimental Procedure . To ensure even drying throughout, it was necessary to use a thin muscle of regular geometrical form. The sartorius muscle of the frog was therefore chosen. The frogs were precooled for some hours at zero. The muscles were then carefully removed at their insertions, wiped on filter paper, and each individual muscle suspended by a silk thread of known weight (see later) in a stoppered bottle, over 0·72 per cent, sodium chloride solution. After standing at 0° C. for 24 hours, to allow of the removal of the lactic acid formed during the manipulation, the muscles were weighed, and rapidly dried by being suspended in bottles over solid calcium chloride. It has already been shown that this method of drying produces a uniform state throughout the muscle (1, p. 187). They were removed at intervals for weighing.

Degradation of ornithine decarboxylase: exposure of the C-terminal target by a polyamine-inducible inhibitory protein

1993 ◽  
Vol 13 (4) ◽  
pp. 2377-2383
Author(s):  
X Li ◽  
P Coffino
Keyword(s):  
Conformational Change ◽  
Ornithine Decarboxylase ◽  
Binding Protein ◽  
Active Form ◽  
Feedback Regulation ◽  
Degradation Process ◽  
Protein Inhibitor ◽  
Inhibitory Protein ◽  
C Terminus ◽  
N Terminus

Polyamine-mediated degradation of vertebrate ornithine decarboxylase (ODC) is associated with the production of antizyme, a reversible tightly binding protein inhibitor of ODC activity. The interaction of antizyme with a binding element near the N terminus of ODC is essential but not sufficient for regulation of the enzyme by polyamines (X. Li and P. Coffino, Mol. Cell. Biol. 12:3556-2562, 1992). We now show that a second element present at the C terminus is required for the degradation process. Antizyme caused a conformational change in ODC, which made the C terminus of ODC more accessible. Blocking the C terminus with antibody prevented degradation. Tethering the C terminus by creating a circularly permuted, enzymatically active form of ODC prevented antizyme-mediated degradation. These data elucidate a form of feedback regulation whereby excess polyamines induce destruction of ODC, the enzyme that initiates their biosynthesis.

scholarly journals Microbiota indigenous milk, mesophilic lipolytic and proteolytic colonial cheese matured, produced at different times of the year

2017 ◽  
Vol 18 (4) ◽  
pp. 549-559
Author(s):  
Elisângela Borsoi Pereira ◽  
Magali Soares dos Santos Pozza ◽  
Paula Martins Olivo ◽  
Osmar Dalla Santa ◽  
Suzana da Cruz Pires ◽  
...  
Keyword(s):  
Weight Loss ◽  
Lactic Acid ◽  
Experimental Design ◽  
Relative Humidity ◽  
Water Activity ◽  
Cultural Importance ◽  
The Third ◽  
Randomized Experimental Design ◽  
Double Factorial ◽  
Production Period

SUMMARY Cheese is the oldest form of preserving milk nutrients having nutritional, economic and cultural importance. The objective of this study was to identify the best time of the year for production, and period, in months, for maturation of traditional colonial cheese, through analysis of water activity, weight loss and counts of lactic acid, mesophilic microorganisms—proteolytic and lipolytic. Records of temperature and relative humidity (RH) were maintained. A completely randomized experimental design was used in a double factorial scheme, considering production periods and maturation times. For all production periods evaluated, there was a significant reduction in the periods for water activity values. The counts of lactic acid bacteria ranged from 104 to 109 CFU/g. There was also stability in the number of colonies for lipolytic mesophilic microorganisms, until the third month of maturation. Low counts of proteolytic mesophiles were observed for the samples produced in May and June (5.70 and 5.53 log), respectively. The production period for the months of May and June corresponding to RH of 80% and average temperatures of 15°C were the most effective for production. Due to the presence of Listeria, it is recommended to respect the minimum time of 60 days of maturation for commercialization.

Conformational changes in the third PDZ domain of the neuronal postsynaptic density protein 95

2019 ◽  
Vol 75 (4) ◽  
pp. 381-391 ◽  
Author(s):  
Ana Camara-Artigas ◽  
Javier Murciano-Calles ◽  
Jose C. Martínez
Keyword(s):  
Binding Site ◽  
Conformational Changes ◽  
Pdz Domain ◽  
Postsynaptic Density ◽  
Crystal Form ◽  
Space Groups ◽  
The Third ◽  
Conformational Plasticity ◽  
Α Helix ◽  
Postsynaptic Density Protein

PDZ domains are protein–protein recognition modules that interact with other proteins through short sequences at the carboxyl terminus. These domains are structurally characterized by a conserved fold composed of six β-strands and two α-helices. The third PDZ domain of the neuronal postsynaptic density protein 95 has an additional α-helix (α3), the role of which is not well known. In previous structures, a succinimide was identified in the β2–β3 loop instead of Asp332. The presence of this modified residue results in conformational changes in α3. In this work, crystallographic structures of the following have been solved: a truncated form of the third PDZ domain of the neuronal postsynaptic density protein 95 from which α3 has been removed, D332P and D332G variants of the protein, and a new crystal form of this domain showing the binding of Asp332 to the carboxylate-binding site of a symmetry-related molecule. Crystals of the wild type and variants were obtained in different space groups, which reflects the conformational plasticity of the domain. Indeed, the overall analysis of these structures suggests that the conformation of the β2–β3 loop is correlated with the fold acquired by α3. The alternate conformation of the β2–β3 loop affects the electrostatics of the carboxylate-binding site and might modulate the binding of different PDZ-binding motifs.

Defining a second epitope for heparin-induced thrombocytopenia/thrombosis antibodies using KKO, a murine HIT-like monoclonal antibody

Blood ◽  
2002 ◽  
Vol 99 (4) ◽  
pp. 1230-1236 ◽  
Author(s):  
Zhong Q. Li ◽  
Weiyi Liu ◽  
Kwang S. Park ◽  
Brue S. Sachais ◽  
Gowthani M. Arepally ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Binding Site ◽  
Binding Sites ◽  
Heparin Therapy ◽  
Common Complication ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
The Third ◽  
N Terminus ◽  
A Site

Heparin-induced thrombocytopenia/thrombosis (HIT/T) is a common complication of heparin therapy that is caused by antibodies to platelet factor 4 (PF4) complexed with heparin. The immune response is polyclonal and polyspecific, ie, more than one neoepitope on PF4 is recognized by HIT/T antibodies. One such epitope has been previously identified; it involves the domain between the third and fourth cysteine residues in PF4 (site 1). However, the binding sites for other HIT/T antibodies remain to be defined. To explore this issue, the binding site of KKO, an HIT/T-like murine monoclonal antibody, was defined. KKO shares a binding site with many HIT/T antibodies on PF4/heparin, but does not bind to site 1 or recognize mouse PF4/heparin. Therefore, the binding of KKO to a series of mouse/human PF4 chimeras complexed with heparin was examined. KKO recognizes a site that requires both the N terminus of PF4 and Pro34, which immediately precedes the third cysteine. Both regions lie on the surface of the PF4 tetramer in sufficient proximity (within 0.74 nm) to form a contiguous antigenic determinant. The 10 of 14 HIT/T sera that require the N terminus of PF4 for antigen recognition also require Pro34 to bind. This epitope, termed site 2, lies adjacent to site 1 in the crystal structure of the PF4 tetramer. Yet sites 1 and 2 can be recognized by distinct populations of antibodies. These studies further help to define a portion of the PF4 tetramer to which self-reactive antibodies develop in patients exposed to heparin.

scholarly journals Erratum

1966 ◽  
Vol 12 (8) ◽  
pp. 490-490
Keyword(s):  
Lactic Acid ◽  
Spectrophotometric Determination ◽  
The Third ◽  
Third Line

Abstract In the article "An Enzymatic-Spectrophotometric Determination on Pyruvic and Lactic Acid in Blood: Methodologic aspects" by J. C. Rosenberg and B. F. Rush in the May issue of the Journal, the third line under Lactic Acid on page 302 erroneously identified NAD+ as NADT. The line should read as follows: semicarbazide solution, 0.6 ml. of the NAD+ solution, and 0.2 ml. of the

The α-Helix Folds More Rapidly at the C-Terminus Than at the N-Terminus

2005 ◽  
Vol 127 (40) ◽  
pp. 13784-13785 ◽  
Author(s):  
Angela Pozo Ramajo ◽  
Sarah A. Petty ◽  
Agnieszka Starzyk ◽  
Martin Volk
Keyword(s):  
C Terminus ◽  
N Terminus ◽  
Α Helix

scholarly journals A Relation between Exopolysaccharide from Lactic Acid Bacteria and Properties of Fermentation Induced Soybean Protein Gels

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 90
Author(s):  
Xiaoyu Yang ◽  
Jiao Feng ◽  
Qianqian Zhu ◽  
Rui Hong ◽  
Liang Li
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Water Distribution ◽  
Soybean Protein ◽  
Production Capacity ◽  
Gel Properties ◽  
Texture Profile ◽  
Protein Gel ◽  
Protein Gels ◽  
Α Helix

Exopolysaccharide (EPS) producing lactic acid bacteria (LAB) is considered to be an effective texture improver. The effect of LAB strains (different EPS production capacity) on physicochemical properties (texture profile, water distribution, rheological properties, and microstructure), protein conformation, and chemical forces of soybean protein gel was investigated. Correlations between EPS yield and gel properties were established. Large masses of EPS were isolated from L. casei fermentation gel (L. casei-G, 677.01 ± 19.82 mg/kg). Gel with the highest hardness (319.74 ± 9.98 g) and water holding capacity (WHC, 87.74 ± 2.00%) was also formed with L. casei. The conversion of β-sheet to α-helix, the increased hydrophobic interaction and ionic bond helped to form an ordered gel network. The yield was positively correlated with hardness, WHC, A22, viscoelasticity, and viscosity, but negatively correlated with A23 (p < 0.05). The macromolecular properties of EPS (especially the yield) and its incompatibility with proteins could be explained as the main reason for improving gel properties. In conclusion, the EPS producing LAB, especially L. casei used in our study, is the best ordinary coagulate replacement in soybean-based products.

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