Severity: Warning
Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 176
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 1034
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3152
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Purpose: To relate NMR relaxation times to instability-related molecular motions of freeze-dried protein formulations and to examine the effect of sugars on these motions.
Methods: Rotating-frame spin-lattice relaxation time (T(1ρ)) was determined for both protein and sugar carbons in freeze-dried lysozyme-sugar (trehalose, sucrose and isomaltose) formulations using solid-state (13)C NMR.
Results: The temperature dependence of T(1ρ) for the lysozyme carbonyl carbons in lysozyme with and without sugars was describable with a model that includes two different types of molecular motion with different correlation times (τ(c)) for the carbon with each τ(c) showing Arrhenius temperature dependence. Both relaxation modes have much smaller relaxation time constant (τ(c)) and temperature coefficient (Ea) than structural relaxation and may be classified as β-relaxation and γ-relaxation. The τ(c) and Ea for γ-relaxation were not affected by sugars, but those for β-relaxation were increased by sucrose, changed little by trehalose, and decreased by isomaltose, suggesting that the β-mobility of the lysozyme carbonyl carbons is decreased by sucrose and increased by isomaltose.
Conclusion: T(1ρ) determined for the lysozyme carbonyl carbons can reflect the effect of sugars on molecular mobility in lysozyme. However, interpretation of relaxation time data is complex and may demand data over an extended temperature range.
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Source |
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http://dx.doi.org/10.1007/s11095-011-0512-8 | DOI Listing |
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