TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation: (I) is prepared by standard recombinant techniques (claimed).Preferred NDO Complex: (I) or its catalytically active fragment has an alpha subunit that comprises an amino acid substitution at position 352 (corresponding to amino acid at position 352 of NDO), in which a naturally occurring amino acid other than phenylalanine (preferably valine) is substituted, and/or it further comprises a substituted amino acid at position 201, 202, 260, 316, 351, 358, 362 or 366 corresponding to position 201, 202, 260, 316, 351, 358, 362 or 366 in NDO. The alpha subunit in (I) comprising an amino acid other than phenylalanine at position 352 has a fully defined amino acid sequence of 449 (S2), or 449 (S32-S36) amino acids as given in the specification. The alpha subunit in (I) with the amino acid substitution corresponding to position 352 in NDO has a fully defined sequence of 449 (S14-S21), 447 (S22, S23), or 451 (S24) amino acids as given in the specification. The alpha subunit comprises amino acids alanine, glutamine or serine at position 201 or leucine or valine at position 202, alanine, leucine or asparagine at position 260, alanine at position 316, asparagine, arginine or serine at position 351, alanine at position 358, alanine at position 362 and tryptophan at position 366. WIDER DISCLOSURE - The following are disclosed:    (1) a primer or probe having 80 percent nucleic acid sequence identity with a DNA segment encoding a polypeptide, its variant or fragment; and    (2) a crystallized form of (I).    SPECIFIC SEQUENCES - The alpha subunit in (I) preferably has a fully defined sequence of 449 amino acids as given in the specification (claimed).    EXAMPLE - Escherichia coil strains DH5alpha and JM109(DE3) were grown to maintain plasmids. Ampicillin or tetracycline was added to final concentrations of 150 and 12 microgram/milliliter, respectively. JM109(DE3) strains carrying plasmids of interest were maintained on minimal medium plates (MSB). Mutagenesis of nahAc was carried out with the Altered Sites II in vitro Mutagenesis System (RTM). A 1.5-kilobase KpnI-XbaI fragment carrying the 3' half of the nahAc gene and the complete nahAd gene from pDTG141 was cloned into KpnI-XbaI-digested pALTER-1. The resulting plasmid, designated pMASTER-1, was used as the template for mutagenesis. The mutagenic oligonucleotide (5'-TTCAGCGAACGGTCGGGCCTGC-3') was designed such that the restriction pattern of the plasmid was altered to facilitate screening for clones carrying the desired mutation. The same T-G base change alters the TTC codon specifying phenylalanine to GTC, which specifies valine. The phosphorylated oligonucleotide used for mutagenesis was synthesized. pMASTER-1 (2 microg) was denatured at room temperature for 5 minutes. The denatured plasmid DNA was precipitated and incubated at -70 degrees Centigrade for 30 minutes. After centrifugation the DNA pellet was dried under vacuum and dissolved in 10 milliMolar Tris, 1 milliMolar EDTA (ethyelene diamine tetraacetate). The nucleotide sequences of both strands of the entire insertion in pMASTER-1 were determined for each mutant. Fluorescent automated DNA sequencing was carried out. After verification of each mutation by restriction digestion and sequence analysis, the 1.5-kilobase KpnI-XbaI fragments carrying each mutation were individually cloned into KpnI-XbaI-digested pDTG141. After this subcloning step, the presence of each mutation was verified by restriction and sequence analyses. The resulting derivatives of pDTG141 were introduced into JM109(DE3) for expression studies. To produce induced cells for biotransformation studies, JM109(DE3) carrying the plasmid (pDTG141-F352V) was grown. JM109(DE3) (pDTG141) was grown under identical conditions to provide the wild type control. Isopropyl-beta-D-thiogalactopyranoside (IPTG) was added to a final concentration of 100 microMolar when culture turbidity reached 0.6 - 0.8 at 660 nanomolar. After a 2.5 hour induction period, biotransformation reactions were initiated. Cultures were spiked with 20 milliMolar glucose, 100 milliMolar phosphate buffer (pH 7.2), and 0.025 percent (weight/volume) substrate. Cultures were incubated at 30 degrees Centigrade with shaking for up to 18 hours. Samples were taken periodically and cells were removed by centrifugation. All extracts were analyzed by gas chromatography mass spectrometry (GC-MS) as a result from biotransformation. Studies showed that incubation of biphenyl with host cells carrying the plasmid (pDTG141-F352V) yielded predominantly 3,4-dihydroxy-3,4-dihydrobiphenyl. This was in contrast to results obtained with the wild type cells, which yielded predominantly the 2,3-dihydroxy-2,3-dihydrobiphenyl. Additionally, incubation of phenanthrene with host cells carrying the plasmid (pDTG141-F352V) yielded predominantly 1,2-dihydroxy-1,2-dihydrophenanthrene, rather than the corresponding 3,4-isomer preferentially formed from the wild type cells.