L-Hydroxyproline

BACKGROUND: Understanding the metabolism of the microbial host is essential for the development and optimization of whole-cell based biocatalytic processes, as it dictates production efficiency. This is especially true for redox biocatalysis where metabolically active cells are employed because of the cofactor/cosubstrate regenerative capacity endogenous in the host. Recombinant Escherichia coli was used for overproducing proline-4-hydroxylase (P4H), a dioxygenase catalyzing the hydroxylation of free L-proline into trans-4-hydroxy-L-proline with a-ketoglutarate (a-KG) as cosubstrate. In this whole-cell biocatalyst, central carbon metabolism provides the required cosubstrate a-KG, coupling P4H biocatalytic performance directly to carbon metabolism and metabolic activity. By applying both experimental and computational biology tools, such as metabolic engineering and (13)C-metabolic flux analysis ((13)C-MFA), we investigated and quantitatively described the physiological, metabolic, and bioenergetic response of the whole-cell biocatalyst to the targeted bioconversion and identified possible metabolic bottlenecks for further rational pathway engineering.

Sandal (Santalum album L) contains several interesting amino acids and amines which are not seen in other plants. This includes cis-4-hydroxy-l-proline in free form in leaves, flowers and seeds while trans-4-hydroxy-l-proline in bound form. Traces of 3, 4 dehydroproline is also detected in sandal leaves. Biosynthesis of cis-4-hydroxy proline indicates that hydroxylation taken place at proline present in peptidyl form especially bound to glutamic acid and aspartic acid. Pyrrolizidine-2-carboxylic acid an interesting isatin positive heterocyclic compound is also present in sandal leaves. Sandal also contains sym. homospermidine which is not present in any other plants till today. Biosynthesis of sym. homospermidine goes by a unique pathway of putrescine oxidation, Schiff base formation, condensation and reduction. Moreover sandal leaves contain γ-glutamyl derivative of the lachrymatory precursor of onion, γ-glutamyl-S-propenyl cysteine superoxide.

Salt stress impairs global agricultural crop production by reducing vegetative growth and yield. Despite this importance, a number of gaps exist in our knowledge about very early metabolic responses that ensue minutes after plants experience salt stress. Surprisingly, this early phase remains almost as a black box. Therefore, systematic studies focussing on very early plant physiological responses to salt stress (in this case NaCl) may enhance our understanding on strategies to develop crop plants with a better performance under saline conditions. In the present study, hydroponically grown Vicia faba L. plants were exposed to 90 min of NaCl stress, whereby every 15 min samples were taken for analyzing short-term physiologic responses. Gas chromatography-mass spectrometry-based metabolite profiles were analysed by calculating a principal component analysis followed by multiple contrast tests. Follow-up experiments were run to analyze downstream effects of the metabolic changes on the physiological level.

CONTEXT: Acquired immunodeficiency syndrome (AIDS) is a serious health problem worldwide. It has been reported that Aglaia andamanica Hiern (Meliaceae) leaves possessed an antiviral effect. Therefore, a search of anti-HIV-1 integrase (HIV-1 IN) agents from A. andamanica is a promising target.