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Assembly Lines (assembly + line)

Distribution by Scientific Domains

Chemistry	66%

Selected Abstracts

Functionally Distinct Modules Operate Two Consecutive ,,,,,,, Double-Bond Shifts in the Rhizoxin Polyketide Assembly Line,

ANGEWANDTE CHEMIE, Issue 8 2010
Björn Kusebauch
Verrückte Bindungen: Die biochemische Analyse des Rhizoxin-Biosynthesewegs zeigte, dass die Dieneinheit nicht im Ganzen, sondern über zwei enzymatische Operationen verschoben wird. Die erste Verschiebung resultiert aus einer formalen ,,,-Dehydratisierung in Modul 7; die zweite Doppelbindung wird zunächst durch Modul 8 erzeugt und dann durch ein ,Verschiebemodul" mit einer neuartigen DH*-Domäne verschoben. ACP = Acyl-Carrier-Protein, DH* = Dehydratase-ähnliche Verschiebedomäne. [source]

Rational Manipulation of Carrier-Domain Geometry in Nonribosomal Peptide Synthetases

CHEMBIOCHEM, Issue 6 2007
Ye Liu
Changing the assembly line. Nonribosomal peptide synthetases are multidomain enzyme assemblies responsible for the biosynthesis of a wide range of therapeutically important natural products. Here we describe an approach to construct stable, domain-specific conjugates of nonribosomal peptide synthetases by using synthetic analogues of coenzyme A. [source]

The impact of absenteeism on the quality of assembly line production: The importance of a specialization requirement

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 1 2008
Ricardo Mateo
Absenteeism among manual workers is without doubt one of the most significant factors that affect the functioning of assembly lines. It is a widely held view that high levels of absenteeism have negative repercussions on the quality and costs of operations. According to the scientific theory of work, workers who temporarily stand in for their absent colleagues affect production quality levels because of a lack of work specialization and experience. However, new and sophisticated automation can eliminate the effect of absenteeism on assembly line production. This article gathered more than 960,000 products produced by different levels of absenteeism. The effects of absenteeism on the quality of products in assembly lines over the course of one year were analyzed. In contrast to established thinking, the empirical evidence presented here confirms that absenteeism does not always produce problems in the quality of products. This evidence can be explained by the need for specialization among manual workers has been reduced by the invention of more sophisticated and specialized machinery. © 2007 Wiley Periodicals, Inc. [source]

Analysis of algorithms for two-stage flowshops with multi-processor task flexibility

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2004
George L. Vairaktarakis
Abstract In this article we introduce a 2-machine flowshop with processing flexibility. Two processing modes are available for each task: namely, processing by the designated processor, and processing simultaneously by both processors. The objective studied is makespan minimization. This production environment is encountered in repetitive manufacturing shops equipped with processors that have the flexibility to execute orders either individually or in coordination. In the latter case, the product designer exploits processing synergies between two processors so as to execute a particular task much faster than a dedicated processor. This type of flowshop environment is also encountered in labor-intensive assembly lines where products moving downstream can be processed either in the designated assembly stations or by pulling together the work teams of adjacent stations. This scheduling problem requires determining the mode of operation of each task, and the subsequent scheduling that preserves the flowshop constraints. We show that the problem is ordinary NP-complete and obtain an optimal solution using a dynamic programming algorithm with considerable computational requirements for medium and large problems. Then, we present a number of dynamic programming relaxations and analyze their worst-case error performance. Finally, we present a polynomial time heuristic with worst-case error performance comparable to that of the dynamic programming relaxations. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004. [source]

Covalent Linkage Mediates Communication between ACP and TE Domains in Modular Polyketide Synthases

CHEMBIOCHEM, Issue 6 2008
Lucky Tran
Abstract Polyketide natural products such as erythromycin A and epothilone are assembled on multienzyme polyketide synthases (PKSs), which consist of modular sets of protein domains. Within these type I systems, the fidelity of biosynthesis depends on the programmed interaction among the multiple domains within each module, centered around the acyl carrier protein (ACP). A detailed understanding of interdomain communication will therefore be vital for attempts to reprogram these pathways by genetic engineering. We report here that the interaction between a representative ACP domain and its downstream thioesterase (TE) is mediated largely by covalent tethering through a short "linker" region, with only a minor energetic contribution from protein,protein molecular recognition. This finding helps explain in part the empirical observation that TE domains can function out of their normal context in engineered assembly lines, and supports the view that overall PKS architecture may dictate at least a subset of interdomain interactions. [source]

Type II Thioesterase Restores Activity of a NRPS Module Stalled with an Aminoacyl-S-enzyme that Cannot Be Elongated

CHEMBIOCHEM, Issue 9 2004
Ellen Yeh
Fidelity and efficiency. Nonribosomal peptide synthetases, which contain domains for the activation (A), thiolation (T), and condensation (C) of amino acids (AA), are high-efficiency, high-fidelity assembly lines for synthesizing peptide natural products. Errors in a single step can have serious consequences for product formation. Type II thioesterases (TEII) might play a critical role in ensuring efficiency and accuracy in these systems, essential features in any attempt to engineer NRPSs to produce novel products. [source]