Dr. B. Sabulal

       Differential scanning calorimetric study of the interactions of some stabilizing amino acids and oligopeptides 

       with hen egg white lysozyme

       B. Sabulal and N. Kishore

       Thermal denaturation of lysozyme has been studied at pH 2 in aqueous mixtures of glycine, alanine, leucine, 

       lysine, diglycine, triglycine, tetraglycine, pentaglycine, glycylleucine and glycyl-glycyl-leucine by high-

       sensitivity differential scanning calorimetry (DSC). The most obvious effect of all the amino acids and peptides

       was to raise the temperature of denaturation t_1/2. Both the calorimetric and van't Hoff enthalpies of denaturation

       increased in the presence of these systems, the ratio of the two enthalpies being nearly unity in each case,

       indicating the validity of the two-state approximation for the unfolding of lysozyme in these cosolute systems.

       The reversibility of the denaturation has been demonstrated by the reversibility of the DSC curves. It has been 

       observed that the peptides provide more thermal stabilization than the corresponding free amino acids. The

       quantitative thermodynamic parameters accompanying the thermal denaturation have been evaluated.

       The observed stabilization of the protein in the presence of these cosolutes has been explained on the basis

       of preferential hydration of the protein and the attenuation of this effect by the hydrophobic and H-bonding

       groups of the amino acids and peptides.

•  Phytochemistry

       Phytochemistry 2006 67: 2469-2473

       Caryophyllene-rich Rhizome Oil of Zingiber nimmonii from South India: Chemical Characterization and 

       Antimicrobial Activity

       Baby Sabulal, Mathew Dan, Anil John J, Rajani Kurup, Nediyamparambu Sukumaran Pradeep, Renju

       Krishna Valsamma and Varughese George

       Volatile oil from the rhizomes of Zingiber nimmonii (J.Graham) Dalzell was isolated, characterized by

       analytical gas chromatography and gas chromatography-mass spectroscopy. Sixty-five constituents

       accounting for 97.5% of the oil were identified. Z. nimmonii rhizome oil is a unique caryophyllene-rich

       natural source with isomeric caryophyllenes, b-caryophyllene (42.2%) and a-humulene (a-caryophyllene,

       27.7%), as its major constituents along with traces of isocaryophyllene. The rhizome oil contained

       71.2% sesquiterpenes, 14.2% oxygenated sesquiterpenes, 8.9% monoterpenes, 1.9% oxygenated

       monoterpenes and 1.3% non-terpenoid constituents. The antimicrobial activity of the oil was tested

       against human and plant pathogenic bacteria and fungi. The oil showed significant inhibitory activity

       against the fungi, Candida glabrata, C. albicans and Aspergillus niger and the bacteria Bacillus subtilis

       and Pseudomonas aeruginosa. No activity was observed against the fungus Fusarium oxysporum.

•  Biochemistry-Proteomics

       Journal of Biological Chemistry 2006 281: 1532-1546

       Formation of a Distinctive Complex between the Inducible Bacterial Lysine Decarboxylase and a Novel AAA⁺

       ATPase

       Jamie Snider, Irina Gutsche, Michelle Lin, Sabulal Baby, Brian Cox, Gareth Butland, Jack Greenblatt, 

       Andrew Emili and Walid A. Houry

       AAA⁺ ATPases are ubiquitous proteins that employ the energy obtained from ATP hydrolysis to remodel

       proteins, DNA, or RNA. The MoxR family of AAA⁺ proteins is widespread throughout bacteria and archaea

       but is largely uncharacterized. Limited work with specific members has suggested a potential role as

       molecular chaperones involved in the assembly of protein complexes. As part of an effort aimed at determining

       the function of novel AAA⁺ chaperones in Escherichia coli, we report the characterization of a representative

       member of the MoxR family, YieN, which we have renamed RavA (regulatory ATPase variant A). We show

       that the ravA gene exists on an operon with another gene encoding a protein, YieM, of unknown function

       containing a Von Willebrand Factor Type A domain. RavA expression is under the control of the s^S 

       transcription factor, and its levels increase toward late log/early stationary phase, consistent with its possible 

       role as a general stress response protein. RavA functions as an ATPase and forms hexameric oligomers.

       Importantly, we demonstrate that RavA interacts strongly with inducible lysine decarboxylase (LdcI or CadA) 

       forming a large cage-like structure consisting of two LdcI decamers linked by a maximum of five RavA

       oligomers. Surprisingly, the activity of LdcI does not appear to be affected by binding to RavA in a number of

       in vitro and in vivo assays, however, complex formation results in the stimulation of RavA ATPase activity.

       Data obtained suggest that the RavA-LdcI interaction may be important for the regulation of RavA activity

       against its targets.

•  Flavour and Fragrance: Chemistry

       Flavour and Fragrance Journal 2007 22: 521-524      

       Phenylbutanoid-rich Rhizome Oil of Zingiber neesanum from Western Ghats, Southern India

       Baby Sabulal, Mathew Dan, Anil John J, Rajani Kurup, Sreeja Purushothaman Chandrika and

       Varughese  George

        Essential oil from the rhizomes of Zingiber neesanum (Graham) Ramamoorthy from the Western Ghats region of   

        southern India was isolated and characterized by GC and GC-MS. Oil constituents were identified by comparison of

        individual mass spectra with databases and the literature, linear retention indices and co-injection. Sixty-one

        constituents, comprising 97.4% of the oil, were identified. Phenylbutanoids, viz. (E)-1-(3’,4’-dimethoxyphenyl)

        butadiene (31.1%), a potential antiinflammatory compound, and (E)-1-(3’,4’-dimethoxyphenyl)but-1-ene (23.1%)

        were isolated from the oil by prep. TLC, characterized by IR, UV, 1H-NMR and MS and quantified by external 

        standardization. (E)-b-ocimene (12.7%), b-pinene (7.4%) and linalool (4.0%) were the major terpenoid constituents